CVS, which stands for Concurrent Versions System, is a client/server application which tracks changes to sets of files. It allows multiple users to work concurrently on files, and then merge their changes back into the main tree (which can be on a remote system). It also allows branching, or maintaining separate versions for files.
There are two vulnerabilities in CVS; one in the server and one in the client. The server vulnerability allows a malicious client to request the contents of any RCS file to which the server has permission, even those not located under $CVSROOT. The client vulnerability allows a malicious server to overwrite files on the client machine anywhere the client has permissions.
Arbitrary files may be read or written on CVS clients and servers by anybody with access to the CVS tree.
There is no known workaround at this time. All users are encouraged to upgrade to the latest stable version of CVS.
All CVS users should upgrade to the latest stable version.
# emerge sync
# emerge -pv ">=dev-util/cvs-1.11.15"
# emerge ">=dev-util/cvs-1.11.15"