diff --git a/web/src/main/java/org/springframework/security/web/util/IpAddressMatcher.java b/web/src/main/java/org/springframework/security/web/util/IpAddressMatcher.java
index cb966c8451..57611e1a51 100644
--- a/web/src/main/java/org/springframework/security/web/util/IpAddressMatcher.java
+++ b/web/src/main/java/org/springframework/security/web/util/IpAddressMatcher.java
@@ -17,7 +17,7 @@ import org.springframework.util.StringUtils;
  * @author Luke Taylor
  * @since 3.0.2
  */
-public class IpAddressMatcher implements RequestMatcher {
+public final class IpAddressMatcher implements RequestMatcher {
     private final int nMaskBits;
     private final InetAddress requiredAddress;
 
@@ -34,19 +34,23 @@ public class IpAddressMatcher implements RequestMatcher {
             ipAddress = addressAndMask[0];
             nMaskBits = Integer.parseInt(addressAndMask[1]);
         } else {
-            nMaskBits = 0;
+            nMaskBits = -1;
         }
         requiredAddress = parseAddress(ipAddress);
     }
 
     public boolean matches(HttpServletRequest request) {
-        InetAddress remoteAddress = parseAddress(request.getRemoteAddr());
+        return matches(request.getRemoteAddr());
+    }
+
+    public boolean matches(String address) {
+        InetAddress remoteAddress = parseAddress(address);
 
         if (!requiredAddress.getClass().equals(remoteAddress.getClass())) {
             return false;
         }
 
-        if (nMaskBits == 0) {
+        if (nMaskBits < 0) {
             return remoteAddress.equals(requiredAddress);
         }
 
diff --git a/web/src/test/java/org/springframework/security/web/util/IpAddressMatcherTests.java b/web/src/test/java/org/springframework/security/web/util/IpAddressMatcherTests.java
index 7ae21a0ad6..e9febc7cd4 100644
--- a/web/src/test/java/org/springframework/security/web/util/IpAddressMatcherTests.java
+++ b/web/src/test/java/org/springframework/security/web/util/IpAddressMatcherTests.java
@@ -28,7 +28,6 @@ public class IpAddressMatcherTests {
         assertTrue(v6matcher.matches(ipv6Request));
     }
 
-
     @Test
     public void ipv6MatcherDoesntMatchIpv4Address() {
         assertFalse(v6matcher.matches(ipv4Request));
@@ -48,4 +47,27 @@ public class IpAddressMatcherTests {
         ipv4Request.setRemoteAddr("192.168.1.159"); // 159 = 0x9f
         assertTrue(matcher.matches(ipv4Request));
     }
+
+    @Test
+    public void ipv6RangeMatches() throws Exception {
+        IpAddressMatcher matcher = new IpAddressMatcher("2001:DB8::/48");
+
+        assertTrue(matcher.matches("2001:DB8:0:0:0:0:0:0"));
+        assertTrue(matcher.matches("2001:DB8:0:0:0:0:0:1"));
+        assertTrue(matcher.matches("2001:DB8:0:FFFF:FFFF:FFFF:FFFF:FFFF"));
+        assertFalse(matcher.matches("2001:DB8:1:0:0:0:0:0"));
+    }
+
+    // SEC-1733
+    @Test
+    public void zeroMaskMatchesAnything() throws Exception {
+        IpAddressMatcher matcher = new IpAddressMatcher("0.0.0.0/0");
+
+        assertTrue(matcher.matches("123.4.5.6"));
+        assertTrue(matcher.matches("192.168.0.159"));
+
+        matcher = new IpAddressMatcher("192.168.0.159/0");
+        assertTrue(matcher.matches("123.4.5.6"));
+        assertTrue(matcher.matches("192.168.0.159"));
+    }
 }