Updated Apache httpd packages that correct a security issue are now
available for CentOS Linux 2.1.
This update has been rated as having important security impact by the Red
Hat Security Response Team.
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
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.