The sys_timer_create function in posix-timers.c for Linux kernel 2.6.x allows local users to cause a denial of service (memory consumption) and possibly bypass memory limits or cause other processes to be killed by creating a large number of posix timers, which are allocated in kernel memory but are not treated as part of the process' memory.
This issue can only be exploited if pending signals (ulimit -i) is set to "unlimited". In case of Red Hat Enterprise Linux version 2.1, 3 and 4 this is not the case and therefore they are not vulnerable to this issue.