I've got a Tomcat 6.0.35 service with a SOAP based webapp protected by Digest Authentication. We are seeing issues with various users getting repeated 401 responses since we upgraded to 6.0.35. Additionally we are getting the following entries in Catalina log: WARNING: A valid entry has been removed from client nonce cache to make room for new entries. A replay attack is now possible. To prevent the possibility of replay attacks, reduce nonceValidity or increase cnonceCacheSize. Further warnings of this type will be suppressed for 5 minutes. Any idea what is going on?