CVE-2016-8745 Apache Tomcat Information Disclosure

Severity: Important

Vendor: The Apache Software Foundation

Versions Affected:
Apache Tomcat 9.0.0.M1 to 9.0.0.M13
Apache Tomcat 8.5.0 to 8.5.8
Apache Tomcat 8.0.0.RC1 to 8.0.39 (new)
Apache Tomcat 7.0.0 to 7.0.73 (new)
Apache Tomcat 6.0.16 to 6.0.48 (new)

Description
A bug in the error handling of the send file code for the NIO HTTP
connector resulted in the current Processor object being added to the
Processor cache multiple times. This in turn meant that the same
Processor could be used for concurrent requests. Sharing a Processor can
result in information leakage between requests including, not not
limited to, session ID and the response body.
The bug was first noticed in 8.5.x onwards where it appears the
refactoring of the Connector code for 8.5.x onwards made it more likely
that the bug was observed. Initially it was thought that the 8.5.x
refactoring introduced the bug but further investigation has shown that
the bug is present in all currently supported Tomcat versions.

Mitigation:
Users of the NIO HTTP connector with the affected versions should apply
one of the following mitigations
- Switch to the BIO HTTP, NIO2 HTTP or APR HTTP connector
- Disable send file
- Upgrade to Apache Tomcat 9.0.0.M15 or later
  (Apache Tomcat 9.0.0.M14 has the fix but was not released)
- Upgrade to Apache Tomcat 8.5.9 or later
- Upgrade to Apache Tomcat 8.0.40 or later when released
- Upgrade to Apache Tomcat 7.0.74 or later when released
- Upgrade to Apache Tomcat 6.0.49 or later when released

Credit:
This issue was reported publicly as Bug 60409 [1] and the security
implications identified by the Tomcat security team.

History:
2016-12-12 Original advisory
2017-01-04 Updated information on affected versions

References:
[1] https://bz.apache.org/bugzilla/show_bug.cgi?id=60409
[2] http://tomcat.apache.org/security-9.html
[3] http://tomcat.apache.org/security-8.html
[3] http://tomcat.apache.org/security-7.html
[3] http://tomcat.apache.org/security-6.html