OpenAFS is a distributed network filesystem.
Russ Allbery, Jeffrey Altman, Dan Hyde and Thomas Mueller discovered a race condition due to an improper handling of the clients callbacks lists.
A remote attacker could construct cases which trigger the race condition, resulting in a server crash.
There is no known workaround at this time.
All OpenAFS users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-fs/openafs-1.4.6"