The Apache HTTP server is one of the most popular web servers on the Internet. The Apache module mod_rewrite provides a rule-based engine to rewrite requested URLs on the fly.
An off-by-one flaw has been found in Apache's mod_rewrite module by Mark Dowd of McAfee Avert Labs. This flaw is exploitable depending on the types of rewrite rules being used.
A remote attacker could exploit the flaw to cause a Denial of Service or execution of arbitrary code. Note that Gentoo Linux is not vulnerable in the default configuration.
There is no known workaround at this time.
All Apache users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose www-servers/apache