Upgrade to Spring Security 4.2.6

Closes gh-13028

spring-boot-dependencies/pom.xml

@@ -166,7 +166,7 @@
 		<spring-plugin.version>1.2.0.RELEASE</spring-plugin.version>
 		<spring-restdocs.version>1.1.3.RELEASE</spring-restdocs.version>
 		<spring-retry.version>1.2.2.RELEASE</spring-retry.version>
-		<spring-security.version>4.2.5.RELEASE</spring-security.version>
+		<spring-security.version>4.2.6.RELEASE</spring-security.version>
 		<spring-security-jwt.version>1.0.9.RELEASE</spring-security-jwt.version>
 		<spring-security-oauth.version>2.0.14.RELEASE</spring-security-oauth.version>
 		<spring-session.version>1.3.2.RELEASE</spring-session.version>