A vulnerability has been discovered by Andi Kleen in the ptrace emulation code for AMD64 platforms when eflags are processed, allowing a local user to obtain elevated priveleges. The Common Vulnerabilities and Exposures project, http://cve.mitre.org, has assigned CAN-2004-0001 to this issue.
Only users of the AMD64 platform are affected: in this scenario, a user may be able to obtain elevated priveleges, including root access. However, no public exploit is known for the vulnerability at this time.
There is no temporary workaround - a kernel upgrade is required. A list of unaffected kernels is provided along with this announcement.
Users are encouraged to upgrade to the latest available sources for their system:
# emerge sync
# emerge -pv your-favourite-sources
# emerge your-favourite-sources
# # Follow usual procedure for compiling and installing a kernel.
# # If you use genkernel, run genkernel as you would do normally.
# # IF YOUR KERNEL IS MARKED as "remerge required!" THEN
# # YOU SHOULD UPDATE YOUR KERNEL EVEN IF PORTAGE
# # REPORTS THAT THE SAME VERSION IS INSTALLED.