diff --git a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/AbstractWebClientReactiveOAuth2AccessTokenResponseClient.java b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/AbstractWebClientReactiveOAuth2AccessTokenResponseClient.java
index da90d58a16..fff6222bb6 100644
--- a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/AbstractWebClientReactiveOAuth2AccessTokenResponseClient.java
+++ b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/AbstractWebClientReactiveOAuth2AccessTokenResponseClient.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,6 +42,7 @@ import org.springframework.web.reactive.function.BodyExtractor;
 import org.springframework.web.reactive.function.BodyInserters;
 import org.springframework.web.reactive.function.client.ClientResponse;
 import org.springframework.web.reactive.function.client.WebClient;
+import org.springframework.web.reactive.function.client.WebClient.RequestHeadersSpec;
 
 /**
  * Abstract base class for all of the {@code WebClientReactive*TokenResponseClient}s that
@@ -70,6 +71,8 @@ public abstract class AbstractWebClientReactiveOAuth2AccessTokenResponseClient<T
 
 	private WebClient webClient = WebClient.builder().build();
 
+	private Converter<T, RequestHeadersSpec<?>> requestEntityConverter = this::validatingPopulateRequest;
+
 	private Converter<T, HttpHeaders> headersConverter = this::populateTokenRequestHeaders;
 
 	private Converter<T, MultiValueMap<String, String>> parametersConverter = this::populateTokenRequestParameters;
@@ -84,15 +87,7 @@ public abstract class AbstractWebClientReactiveOAuth2AccessTokenResponseClient<T
 	public Mono<OAuth2AccessTokenResponse> getTokenResponse(T grantRequest) {
 		Assert.notNull(grantRequest, "grantRequest cannot be null");
 		// @formatter:off
-		return Mono.defer(() -> this.webClient.post()
-				.uri(clientRegistration(grantRequest).getProviderDetails().getTokenUri())
-				.headers((headers) -> {
-					HttpHeaders headersToAdd = getHeadersConverter().convert(grantRequest);
-					if (headersToAdd != null) {
-						headers.addAll(headersToAdd);
-					}
-				})
-				.body(createTokenRequestBody(grantRequest))
+		return Mono.defer(() -> this.requestEntityConverter.convert(grantRequest)
 				.exchange()
 				.flatMap((response) -> readTokenResponse(grantRequest, response))
 		);
@@ -106,6 +101,34 @@ public abstract class AbstractWebClientReactiveOAuth2AccessTokenResponseClient<T
 	 */
 	abstract ClientRegistration clientRegistration(T grantRequest);
 
+	private RequestHeadersSpec<?> validatingPopulateRequest(T grantRequest) {
+		validateClientAuthenticationMethod(grantRequest);
+		return populateRequest(grantRequest);
+	}
+
+	private void validateClientAuthenticationMethod(T grantRequest) {
+		ClientRegistration clientRegistration = grantRequest.getClientRegistration();
+		ClientAuthenticationMethod clientAuthenticationMethod = clientRegistration.getClientAuthenticationMethod();
+		boolean supportedClientAuthenticationMethod = clientAuthenticationMethod.equals(ClientAuthenticationMethod.NONE)
+				|| clientAuthenticationMethod.equals(ClientAuthenticationMethod.CLIENT_SECRET_BASIC)
+				|| clientAuthenticationMethod.equals(ClientAuthenticationMethod.CLIENT_SECRET_POST);
+		if (!supportedClientAuthenticationMethod) {
+			throw new IllegalArgumentException(String.format(
+					"This class supports `client_secret_basic`, `client_secret_post`, and `none` by default. Client [%s] is using [%s] instead. Please use a supported client authentication method, or use `set/addParametersConverter` or `set/addHeadersConverter` to supply an instance that supports [%s].",
+					clientRegistration.getRegistrationId(), clientAuthenticationMethod, clientAuthenticationMethod));
+		}
+	}
+
+	private RequestHeadersSpec<?> populateRequest(T grantRequest) {
+		return this.webClient.post().uri(clientRegistration(grantRequest).getProviderDetails().getTokenUri())
+				.headers((headers) -> {
+					HttpHeaders headersToAdd = getHeadersConverter().convert(grantRequest);
+					if (headersToAdd != null) {
+						headers.addAll(headersToAdd);
+					}
+				}).body(createTokenRequestBody(grantRequest));
+	}
+
 	/**
 	 * Populates the headers for the token request.
 	 * @param grantRequest the grant request
@@ -280,6 +303,7 @@ public abstract class AbstractWebClientReactiveOAuth2AccessTokenResponseClient<T
 	public final void setHeadersConverter(Converter<T, HttpHeaders> headersConverter) {
 		Assert.notNull(headersConverter, "headersConverter cannot be null");
 		this.headersConverter = headersConverter;
+		this.requestEntityConverter = this::populateRequest;
 	}
 
 	/**
@@ -307,6 +331,7 @@ public abstract class AbstractWebClientReactiveOAuth2AccessTokenResponseClient<T
 			}
 			return headers;
 		};
+		this.requestEntityConverter = this::populateRequest;
 	}
 
 	/**
@@ -331,6 +356,7 @@ public abstract class AbstractWebClientReactiveOAuth2AccessTokenResponseClient<T
 	public final void setParametersConverter(Converter<T, MultiValueMap<String, String>> parametersConverter) {
 		Assert.notNull(parametersConverter, "parametersConverter cannot be null");
 		this.parametersConverter = parametersConverter;
+		this.requestEntityConverter = this::populateRequest;
 	}
 
 	/**
@@ -357,6 +383,7 @@ public abstract class AbstractWebClientReactiveOAuth2AccessTokenResponseClient<T
 			}
 			return parameters;
 		};
+		this.requestEntityConverter = this::populateRequest;
 	}
 
 	/**
diff --git a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/ClientAuthenticationMethodValidatingRequestEntityConverter.java b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/ClientAuthenticationMethodValidatingRequestEntityConverter.java
new file mode 100644
index 0000000000..1c6068b08b
--- /dev/null
+++ b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/ClientAuthenticationMethodValidatingRequestEntityConverter.java
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.security.oauth2.client.endpoint;
+
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.http.RequestEntity;
+import org.springframework.security.oauth2.client.registration.ClientRegistration;
+import org.springframework.security.oauth2.core.ClientAuthenticationMethod;
+import org.springframework.util.Assert;
+
+class ClientAuthenticationMethodValidatingRequestEntityConverter<T extends AbstractOAuth2AuthorizationGrantRequest>
+		implements Converter<T, RequestEntity<?>> {
+
+	private final Converter<T, RequestEntity<?>> delegate;
+
+	ClientAuthenticationMethodValidatingRequestEntityConverter(Converter<T, RequestEntity<?>> delegate) {
+		this.delegate = delegate;
+	}
+
+	@Override
+	public RequestEntity<?> convert(T grantRequest) {
+		ClientRegistration clientRegistration = grantRequest.getClientRegistration();
+		ClientAuthenticationMethod clientAuthenticationMethod = clientRegistration.getClientAuthenticationMethod();
+		String registrationId = clientRegistration.getRegistrationId();
+		boolean supportedClientAuthenticationMethod = clientAuthenticationMethod.equals(ClientAuthenticationMethod.NONE)
+				|| clientAuthenticationMethod.equals(ClientAuthenticationMethod.CLIENT_SECRET_BASIC)
+				|| clientAuthenticationMethod.equals(ClientAuthenticationMethod.CLIENT_SECRET_POST);
+		Assert.isTrue(supportedClientAuthenticationMethod, () -> String.format(
+				"This class supports `client_secret_basic`, `client_secret_post`, and `none` by default. Client [%s] is using [%s] instead. Please use a supported client authentication method, or use `setRequestEntityConverter` to supply an instance that supports [%s].",
+				registrationId, clientAuthenticationMethod, clientAuthenticationMethod));
+		return this.delegate.convert(grantRequest);
+	}
+
+}
diff --git a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultAuthorizationCodeTokenResponseClient.java b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultAuthorizationCodeTokenResponseClient.java
index d2b7587f90..179e564599 100644
--- a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultAuthorizationCodeTokenResponseClient.java
+++ b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultAuthorizationCodeTokenResponseClient.java
@@ -58,7 +58,8 @@ public final class DefaultAuthorizationCodeTokenResponseClient
 
 	private static final String INVALID_TOKEN_RESPONSE_ERROR_CODE = "invalid_token_response";
 
-	private Converter<OAuth2AuthorizationCodeGrantRequest, RequestEntity<?>> requestEntityConverter = new OAuth2AuthorizationCodeGrantRequestEntityConverter();
+	private Converter<OAuth2AuthorizationCodeGrantRequest, RequestEntity<?>> requestEntityConverter = new ClientAuthenticationMethodValidatingRequestEntityConverter<>(
+			new OAuth2AuthorizationCodeGrantRequestEntityConverter());
 
 	private RestOperations restOperations;
 
diff --git a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultClientCredentialsTokenResponseClient.java b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultClientCredentialsTokenResponseClient.java
index a1ee225a94..71f80977f5 100644
--- a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultClientCredentialsTokenResponseClient.java
+++ b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultClientCredentialsTokenResponseClient.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -58,7 +58,8 @@ public final class DefaultClientCredentialsTokenResponseClient
 
 	private static final String INVALID_TOKEN_RESPONSE_ERROR_CODE = "invalid_token_response";
 
-	private Converter<OAuth2ClientCredentialsGrantRequest, RequestEntity<?>> requestEntityConverter = new OAuth2ClientCredentialsGrantRequestEntityConverter();
+	private Converter<OAuth2ClientCredentialsGrantRequest, RequestEntity<?>> requestEntityConverter = new ClientAuthenticationMethodValidatingRequestEntityConverter<>(
+			new OAuth2ClientCredentialsGrantRequestEntityConverter());
 
 	private RestOperations restOperations;
 
diff --git a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultJwtBearerTokenResponseClient.java b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultJwtBearerTokenResponseClient.java
index feae305eda..fa145da534 100644
--- a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultJwtBearerTokenResponseClient.java
+++ b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultJwtBearerTokenResponseClient.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -56,7 +56,8 @@ public final class DefaultJwtBearerTokenResponseClient
 
 	private static final String INVALID_TOKEN_RESPONSE_ERROR_CODE = "invalid_token_response";
 
-	private Converter<JwtBearerGrantRequest, RequestEntity<?>> requestEntityConverter = new JwtBearerGrantRequestEntityConverter();
+	private Converter<JwtBearerGrantRequest, RequestEntity<?>> requestEntityConverter = new ClientAuthenticationMethodValidatingRequestEntityConverter<>(
+			new JwtBearerGrantRequestEntityConverter());
 
 	private RestOperations restOperations;
 
diff --git a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultRefreshTokenTokenResponseClient.java b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultRefreshTokenTokenResponseClient.java
index 8550d077c0..0cadede9b3 100644
--- a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultRefreshTokenTokenResponseClient.java
+++ b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/DefaultRefreshTokenTokenResponseClient.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -55,7 +55,8 @@ public final class DefaultRefreshTokenTokenResponseClient
 
 	private static final String INVALID_TOKEN_RESPONSE_ERROR_CODE = "invalid_token_response";
 
-	private Converter<OAuth2RefreshTokenGrantRequest, RequestEntity<?>> requestEntityConverter = new OAuth2RefreshTokenGrantRequestEntityConverter();
+	private Converter<OAuth2RefreshTokenGrantRequest, RequestEntity<?>> requestEntityConverter = new ClientAuthenticationMethodValidatingRequestEntityConverter<>(
+			new OAuth2RefreshTokenGrantRequestEntityConverter());
 
 	private RestOperations restOperations;
 
diff --git a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultAuthorizationCodeTokenResponseClientTests.java b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultAuthorizationCodeTokenResponseClientTests.java
index 10ef7a95ed..c12b28fcfd 100644
--- a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultAuthorizationCodeTokenResponseClientTests.java
+++ b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultAuthorizationCodeTokenResponseClientTests.java
@@ -370,6 +370,28 @@ public class DefaultAuthorizationCodeTokenResponseClientTests {
 						+ "the OAuth 2.0 Access Token Response");
 	}
 
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenCustomClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(new ClientAuthenticationMethod("basic")).build();
+		OAuth2AuthorizationCodeGrantRequest authorizationCodeGrantRequest = authorizationCodeGrantRequest(
+				clientRegistration);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.tokenResponseClient.getTokenResponse(authorizationCodeGrantRequest));
+	}
+
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenUnsupportedClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_JWT).build();
+		OAuth2AuthorizationCodeGrantRequest authorizationCodeGrantRequest = authorizationCodeGrantRequest(
+				clientRegistration);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.tokenResponseClient.getTokenResponse(authorizationCodeGrantRequest));
+	}
+
 	private OAuth2AuthorizationCodeGrantRequest authorizationCodeGrantRequest(ClientRegistration clientRegistration) {
 		OAuth2AuthorizationRequest authorizationRequest = OAuth2AuthorizationRequest.authorizationCode()
 				.clientId(clientRegistration.getClientId()).state("state-1234")
diff --git a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultClientCredentialsTokenResponseClientTests.java b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultClientCredentialsTokenResponseClientTests.java
index cbc39a4321..aa7c199404 100644
--- a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultClientCredentialsTokenResponseClientTests.java
+++ b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultClientCredentialsTokenResponseClientTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -379,6 +379,28 @@ public class DefaultClientCredentialsTokenResponseClientTests {
 						"[invalid_token_response] An error occurred while attempting to retrieve the OAuth 2.0 Access Token Response");
 	}
 
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenCustomClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(new ClientAuthenticationMethod("basic")).build();
+		OAuth2ClientCredentialsGrantRequest clientCredentialsGrantRequest = new OAuth2ClientCredentialsGrantRequest(
+				clientRegistration);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.tokenResponseClient.getTokenResponse(clientCredentialsGrantRequest));
+	}
+
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenUnsupportedClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_JWT).build();
+		OAuth2ClientCredentialsGrantRequest clientCredentialsGrantRequest = new OAuth2ClientCredentialsGrantRequest(
+				clientRegistration);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.tokenResponseClient.getTokenResponse(clientCredentialsGrantRequest));
+	}
+
 	private MockResponse jsonResponse(String json) {
 		return new MockResponse().setHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE).setBody(json);
 	}
diff --git a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultJwtBearerTokenResponseClientTests.java b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultJwtBearerTokenResponseClientTests.java
index 14c27c993e..28988301fd 100644
--- a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultJwtBearerTokenResponseClientTests.java
+++ b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultJwtBearerTokenResponseClientTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -243,6 +243,26 @@ public class DefaultJwtBearerTokenResponseClientTests {
 						+ "retrieve the OAuth 2.0 Access Token Response");
 	}
 
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenCustomClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(new ClientAuthenticationMethod("basic")).build();
+		JwtBearerGrantRequest jwtBearerGrantRequest = new JwtBearerGrantRequest(clientRegistration, this.jwtAssertion);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.tokenResponseClient.getTokenResponse(jwtBearerGrantRequest));
+	}
+
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenUnsupportedClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_JWT).build();
+		JwtBearerGrantRequest jwtBearerGrantRequest = new JwtBearerGrantRequest(clientRegistration, this.jwtAssertion);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.tokenResponseClient.getTokenResponse(jwtBearerGrantRequest));
+	}
+
 	private MockResponse jsonResponse(String json) {
 		return new MockResponse().setHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE).setBody(json);
 	}
diff --git a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultRefreshTokenTokenResponseClientTests.java b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultRefreshTokenTokenResponseClientTests.java
index be563fe3d2..1bef2b8578 100644
--- a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultRefreshTokenTokenResponseClientTests.java
+++ b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/DefaultRefreshTokenTokenResponseClientTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -313,6 +313,28 @@ public class DefaultRefreshTokenTokenResponseClientTests {
 						+ "retrieve the OAuth 2.0 Access Token Response");
 	}
 
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenCustomClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(new ClientAuthenticationMethod("basic")).build();
+		OAuth2RefreshTokenGrantRequest refreshTokenGrantRequest = new OAuth2RefreshTokenGrantRequest(clientRegistration,
+				this.accessToken, this.refreshToken);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.tokenResponseClient.getTokenResponse(refreshTokenGrantRequest));
+	}
+
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenUnsupportedClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_JWT).build();
+		OAuth2RefreshTokenGrantRequest refreshTokenGrantRequest = new OAuth2RefreshTokenGrantRequest(clientRegistration,
+				this.accessToken, this.refreshToken);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.tokenResponseClient.getTokenResponse(refreshTokenGrantRequest));
+	}
+
 	private MockResponse jsonResponse(String json) {
 		return new MockResponse().setHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE).setBody(json);
 	}
diff --git a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveAuthorizationCodeTokenResponseClientTests.java b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveAuthorizationCodeTokenResponseClientTests.java
index bdc682a269..e3f59024da 100644
--- a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveAuthorizationCodeTokenResponseClientTests.java
+++ b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveAuthorizationCodeTokenResponseClientTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -500,4 +500,26 @@ public class WebClientReactiveAuthorizationCodeTokenResponseClientTests {
 
 	}
 
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenCustomClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(new ClientAuthenticationMethod("basic")).build();
+		OAuth2AuthorizationCodeGrantRequest authorizationCodeGrantRequest = authorizationCodeGrantRequest(
+				clientRegistration);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.tokenResponseClient.getTokenResponse(authorizationCodeGrantRequest).block());
+	}
+
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenUnsupportedClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_JWT).build();
+		OAuth2AuthorizationCodeGrantRequest authorizationCodeGrantRequest = authorizationCodeGrantRequest(
+				clientRegistration);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.tokenResponseClient.getTokenResponse(authorizationCodeGrantRequest).block());
+	}
+
 }
diff --git a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveClientCredentialsTokenResponseClientTests.java b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveClientCredentialsTokenResponseClientTests.java
index 16933ab2ef..010ec7a6cd 100644
--- a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveClientCredentialsTokenResponseClientTests.java
+++ b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveClientCredentialsTokenResponseClientTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -448,4 +448,26 @@ public class WebClientReactiveClientCredentialsTokenResponseClientTests {
 
 	}
 
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenCustomClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(new ClientAuthenticationMethod("basic")).build();
+		OAuth2ClientCredentialsGrantRequest clientCredentialsGrantRequest = new OAuth2ClientCredentialsGrantRequest(
+				clientRegistration);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.client.getTokenResponse(clientCredentialsGrantRequest).block());
+	}
+
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenUnsupportedClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_JWT).build();
+		OAuth2ClientCredentialsGrantRequest clientCredentialsGrantRequest = new OAuth2ClientCredentialsGrantRequest(
+				clientRegistration);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.client.getTokenResponse(clientCredentialsGrantRequest).block());
+	}
+
 }
diff --git a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveJwtBearerTokenResponseClientTests.java b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveJwtBearerTokenResponseClientTests.java
index d221511cc3..2545985573 100644
--- a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveJwtBearerTokenResponseClientTests.java
+++ b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveJwtBearerTokenResponseClientTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -367,6 +367,26 @@ public class WebClientReactiveJwtBearerTokenResponseClientTests {
 		assertThat(response.getAccessToken().getScopes()).isEmpty();
 	}
 
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenCustomClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(new ClientAuthenticationMethod("basic")).build();
+		JwtBearerGrantRequest jwtBearerGrantRequest = new JwtBearerGrantRequest(clientRegistration, this.jwtAssertion);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.client.getTokenResponse(jwtBearerGrantRequest).block());
+	}
+
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenUnsupportedClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistration
+				.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_JWT).build();
+		JwtBearerGrantRequest jwtBearerGrantRequest = new JwtBearerGrantRequest(clientRegistration, this.jwtAssertion);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.client.getTokenResponse(jwtBearerGrantRequest).block());
+	}
+
 	private void enqueueJson(String body) {
 		MockResponse response = new MockResponse().setBody(body).setHeader(HttpHeaders.CONTENT_TYPE,
 				MediaType.APPLICATION_JSON_VALUE);
diff --git a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveRefreshTokenTokenResponseClientTests.java b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveRefreshTokenTokenResponseClientTests.java
index 4d2c945237..2b2401fb62 100644
--- a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveRefreshTokenTokenResponseClientTests.java
+++ b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/endpoint/WebClientReactiveRefreshTokenTokenResponseClientTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -462,4 +462,26 @@ public class WebClientReactiveRefreshTokenTokenResponseClientTests {
 
 	}
 
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenCustomClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistrationBuilder
+				.clientAuthenticationMethod(new ClientAuthenticationMethod("basic")).build();
+		OAuth2RefreshTokenGrantRequest refreshTokenGrantRequest = new OAuth2RefreshTokenGrantRequest(clientRegistration,
+				this.accessToken, this.refreshToken);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.tokenResponseClient.getTokenResponse(refreshTokenGrantRequest).block());
+	}
+
+	// gh-13144
+	@Test
+	public void getTokenResponseWhenUnsupportedClientAuthenticationMethodThenIllegalArgument() {
+		ClientRegistration clientRegistration = this.clientRegistrationBuilder
+				.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_JWT).build();
+		OAuth2RefreshTokenGrantRequest refreshTokenGrantRequest = new OAuth2RefreshTokenGrantRequest(clientRegistration,
+				this.accessToken, this.refreshToken);
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> this.tokenResponseClient.getTokenResponse(refreshTokenGrantRequest).block());
+	}
+
 }