CentOS Errata and Security Advisory CESA-2006:0618-01
The Apache HTTP Server is a popular Web server available for free.
A bug was found in Apache where an invalid Expect header sent to the server was returned to the user in an unescaped error message. This could allow an attacker to perform a cross-site scripting attack if a victim was tricked into connecting to a site and sending a carefully crafted Expect header. (CVE-2006-3918)
While a web browser cannot be forced to send an arbitrary Expect header by a third-party attacker, it was recently discovered that certain versions of the Flash plugin can manipulate request headers. If users running such versions can be persuaded to load a web page with a malicious Flash applet, a cross-site scripting attack against the server may be possible.
Users of Apache should upgrade to these updated packages, which contain a backported patch to correct this issue.
Merged security bulletin from advisories: http://lists.centos.org/pipermail/centos-announce/2006-August/025166.html
Affected packages: apache apache-devel apache-manual
Upstream details at: https://rhn.redhat.com/errata/rh21as-errata.html