diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/security/authc/support/UsernamePasswordToken.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/security/authc/support/UsernamePasswordToken.java
index 4fdf32608dd..d8e58c29d23 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/security/authc/support/UsernamePasswordToken.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/security/authc/support/UsernamePasswordToken.java
@@ -5,6 +5,7 @@
  */
 package org.elasticsearch.xpack.core.security.authc.support;
 
+import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.settings.SecureString;
 import org.elasticsearch.common.util.concurrent.ThreadContext;
 import org.elasticsearch.xpack.core.security.authc.AuthenticationToken;
@@ -20,6 +21,8 @@ public class UsernamePasswordToken implements AuthenticationToken {
 
     public static final String BASIC_AUTH_PREFIX = "Basic ";
     public static final String BASIC_AUTH_HEADER = "Authorization";
+    // authorization scheme check is case-insensitive
+    private static final boolean IGNORE_CASE_AUTH_HEADER_MATCH = true;
     private final String username;
     private final SecureString password;
 
@@ -79,15 +82,15 @@ public class UsernamePasswordToken implements AuthenticationToken {
 
     public static UsernamePasswordToken extractToken(ThreadContext context) {
         String authStr = context.getHeader(BASIC_AUTH_HEADER);
-        if (authStr == null) {
-            return null;
-        }
-
         return extractToken(authStr);
     }
 
     private static UsernamePasswordToken extractToken(String headerValue) {
-        if (headerValue.startsWith(BASIC_AUTH_PREFIX) == false) {
+        if (Strings.isNullOrEmpty(headerValue)) {
+            return null;
+        }
+        if (headerValue.regionMatches(IGNORE_CASE_AUTH_HEADER_MATCH, 0, BASIC_AUTH_PREFIX, 0,
+                BASIC_AUTH_PREFIX.length()) == false) {
             // the header does not start with 'Basic ' so we cannot use it, but it may be valid for another realm
             return null;
         }
diff --git a/x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/authc/TokenService.java b/x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/authc/TokenService.java
index 2934fb8062d..8b6dd8295d3 100644
--- a/x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/authc/TokenService.java
+++ b/x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/authc/TokenService.java
@@ -1007,7 +1007,7 @@ public final class TokenService extends AbstractComponent {
      */
     private String getFromHeader(ThreadContext threadContext) {
         String header = threadContext.getHeader("Authorization");
-        if (Strings.hasLength(header) && header.startsWith("Bearer ")
+        if (Strings.hasText(header) && header.regionMatches(true, 0, "Bearer ", 0, "Bearer ".length())
                 && header.length() > "Bearer ".length()) {
             return header.substring("Bearer ".length());
         }
diff --git a/x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/TokenServiceTests.java b/x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/TokenServiceTests.java
index 28cf4bf95c9..d5e67f3996a 100644
--- a/x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/TokenServiceTests.java
+++ b/x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/TokenServiceTests.java
@@ -71,6 +71,7 @@ import static java.time.Clock.systemUTC;
 import static org.elasticsearch.repositories.ESBlobStoreTestCase.randomBytes;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.notNullValue;
+import static org.hamcrest.Matchers.nullValue;
 import static org.mockito.Matchers.any;
 import static org.mockito.Matchers.anyString;
 import static org.mockito.Matchers.eq;
@@ -162,7 +163,7 @@ public class TokenServiceTests extends ESTestCase {
         mockGetTokenFromId(token);
 
         ThreadContext requestContext = new ThreadContext(Settings.EMPTY);
-        requestContext.putHeader("Authorization", "Bearer " + tokenService.getUserTokenString(token));
+        requestContext.putHeader("Authorization", randomFrom("Bearer ", "BEARER ", "bearer ") + tokenService.getUserTokenString(token));
 
         try (ThreadContext.StoredContext ignore = requestContext.newStoredContext(true)) {
             PlainActionFuture<UserToken> future = new PlainActionFuture<>();
@@ -183,6 +184,21 @@ public class TokenServiceTests extends ESTestCase {
         }
     }
 
+    public void testInvalidAuthorizationHeader() throws Exception {
+        TokenService tokenService = new TokenService(tokenServiceEnabledSettings, systemUTC(), client, securityIndex, clusterService);
+        ThreadContext requestContext = new ThreadContext(Settings.EMPTY);
+        String token = randomFrom("", "          ");
+        String authScheme = randomFrom("Bearer ", "BEARER ", "bearer ", "Basic ");
+        requestContext.putHeader("Authorization", authScheme + token);
+
+        try (ThreadContext.StoredContext ignore = requestContext.newStoredContext(true)) {
+            PlainActionFuture<UserToken> future = new PlainActionFuture<>();
+            tokenService.getAndValidateToken(requestContext, future);
+            UserToken serialized = future.get();
+            assertThat(serialized, nullValue());
+        }
+    }
+
     public void testRotateKey() throws Exception {
         TokenService tokenService = new TokenService(tokenServiceEnabledSettings, systemUTC(), client, securityIndex, clusterService);
         Authentication authentication = new Authentication(new User("joe", "admin"), new RealmRef("native_realm", "native", "node1"), null);
diff --git a/x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/support/UsernamePasswordTokenTests.java b/x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/support/UsernamePasswordTokenTests.java
index 57c45279884..86b9635851b 100644
--- a/x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/support/UsernamePasswordTokenTests.java
+++ b/x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/support/UsernamePasswordTokenTests.java
@@ -45,7 +45,8 @@ public class UsernamePasswordTokenTests extends ESTestCase {
 
     public void testExtractToken() throws Exception {
         ThreadContext threadContext = new ThreadContext(Settings.EMPTY);
-        String header = "Basic " + Base64.getEncoder().encodeToString("user1:test123".getBytes(StandardCharsets.UTF_8));
+        final String header = randomFrom("Basic ", "basic ", "BASIC ")
+                + Base64.getEncoder().encodeToString("user1:test123".getBytes(StandardCharsets.UTF_8));
         threadContext.putHeader(UsernamePasswordToken.BASIC_AUTH_HEADER, header);
         UsernamePasswordToken token = UsernamePasswordToken.extractToken(threadContext);
         assertThat(token, notNullValue());
@@ -54,7 +55,7 @@ public class UsernamePasswordTokenTests extends ESTestCase {
     }
 
     public void testExtractTokenInvalid() throws Exception {
-        String[] invalidValues = { "Basic ", "Basic f" };
+        final String[] invalidValues = { "Basic ", "Basic f", "basic " };
         for (String value : invalidValues) {
             ThreadContext threadContext = new ThreadContext(Settings.EMPTY);
             threadContext.putHeader(UsernamePasswordToken.BASIC_AUTH_HEADER, value);
@@ -70,7 +71,7 @@ public class UsernamePasswordTokenTests extends ESTestCase {
 
     public void testHeaderNotMatchingReturnsNull() {
         ThreadContext threadContext = new ThreadContext(Settings.EMPTY);
-        String header = randomFrom("BasicBroken", "invalid", "Basic");
+        final String header = randomFrom("Basic", "BasicBroken", "invalid", "   basic   ");
         threadContext.putHeader(UsernamePasswordToken.BASIC_AUTH_HEADER, header);
         UsernamePasswordToken extracted = UsernamePasswordToken.extractToken(threadContext);
         assertThat(extracted, nullValue());