A flaw in bounds checking in do_brk in the Linux kernel before 2.4.23
can allow a local user to gain root privileges.
The URL below gives the (2 line) patch that corrects this issue.
Although the issue was commited on October 2nd 2003 it was not
believed to be exploitable for privilege escalation. Working exploits
for this issue have been found in the wild.
Users of Red Hat Enterprise Linux 3 should upgrade to the kernel
packages provided by RHBA-2003:308 released on 30th October 2003 which
already contained a patch to correct this issue.
Updated packages for RHEL 2.1 containing just the patch referenced
above are currently in QA. This issue will be public on 1st Dec 2003.