Secunia

A security issue has been reported in FreeBSD, which can be exploited by malicious people to bypass the firewall ruleset.

The problem is caused due to insufficient concurrency handling in the ipfw tables lookup code. This may lead to the corruption of cached address entries and cause some packets to be incorrectly matched.

Successful exploitation may allow some packets to pass through the firewall when they should have been dropped.

The security issue only affects Symmetric Multi-Processor (SMP) systems, or Uni-Processor (UP) systems with the non-default PREEMPTION kernel option enabled.

Solution
Update FreeBSD or apply patch.
Further details available in Customer Area

Provided and/or discovered by
The vendor credits Max Laier.

Original Advisory
ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:13.ipfw.asc

Deep Links
Links available in Customer Area