fs/exec.c in Linux 2.6, when one thread is tracing another thread that shares the same memory map, might allow local users to cause a denial of service (deadlock) by forcing a core dump when the traced thread is in the TASK_TRACED state.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11473
http://www.ubuntu.com/usn/usn-199-1
http://www.securityfocus.com/bid/15049
http://www.redhat.com/support/errata/RHSA-2006-0437.html
http://www.redhat.com/support/errata/RHSA-2005-420.html
http://www.mandriva.com/security/advisories?name=MDKSA-2006:072
http://www.debian.org/security/2005/dsa-922
http://support.avaya.com/elmodocs2/security/ASA-2006-180.htm
http://secunia.com/advisories/21983
http://secunia.com/advisories/21136
http://secunia.com/advisories/18056