The mod_auth_mellon module before 0.8.1 allows remote attackers to cause a denial of service (Apache HTTP server crash) via a crafted logout request that triggers a read of uninitialized data.
https://postlister.uninett.no/sympa/arc/modmellon/2014-11/msg00000.html
https://github.com/UNINETT/mod_auth_mellon/commit/0f5b4fd860fa7e3a6c47201637aab05395f32647
http://secunia.com/advisories/62125
http://secunia.com/advisories/62094