The zlib version shipped in the 8u151, 7u161 JDK releases was updated to zlib v1.2.11. The deflate functionality in this version causes a compatibility issue with Tomcat v7.x. Server responses can appear as corrupt or can fail to be decoded. The issue is seen if Tomcat is using compression (e.g. compression="on" in server.xml). This issue is being fixed via JDK-8189789 [https://bugs.openjdk.java.net/browse/JDK-8189789]. Users could disable the compression mode on their Tomcat servers as a workaround. Tomcat versions 8.x and later don't appear to be affected.