Ilja van Sprundel reported a vulnerability in the passwd application of shadow, which potentially can be exploited by malicious, local users to perform certain actions with escalated privileges.

The vulnerability is due to missing checks in passwd for whether the "setuid()" call has succeeded, when started with the -f, -g, or -s option. This can potentially be exploited to launch chfn, chsh, or gpasswd with root privileges, which may allow the user to perform certain actions as the root user.

Successful exploitation allows to perform certain actions with escalated privileges, but requires that PAM is configured with a maximum number of user processes.

This vulnerability was reported in version 4.0.3 and 4.0.13. Prior versions may be also affected.

Solution
Update to version 4.0.14 or later.
Further details available to Secunia VIM customers

Provided and/or discovered by
Ilja van Sprundel

Changelog
Further details available to Secunia VIM customers

Original Advisory
http://www.ubuntu.com/usn/usn-308-1

Deep Links
Links available to Secunia VIM customers