Updated Fetchmail packages are available for CentOS Linux Advanced Server which close a remotely-exploitable vulnerability in unpatched versions of Fetchmail prior to 6.1.0.
Fetchmail is a remote mail retrieval and forwarding utility intended for use over on-demand TCP/IP links such as SLIP and PPP connections. Two bugs have been found in the header parsing code in versions of Fetchmail prior to 6.1.0. The first bug allows a remote attacker to crash Fetchmail by sending a carefully crafted DNS packet. The second bug allows a remote attacker to carefully craft an email in such a way that when it is parsed by Fetchmail a heap overflow occurs, allowing remote arbitrary code execution. Both of these bugs are only exploitable if Fetchmail is being used in multidrop mode (using the "multiple-local-recipients" feature). All users of Fetchmail are advised to upgrade to the errata packages containing a backported fix which is not vulnerable to these issues.