Updated Apache httpd packages that correct security issues and resolve bugs are now available for CentOS Linux 3 and 4. This update has been rated as having moderate 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 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. On CentOS Linux 3 and 4 systems, due to an unrelated issue in the handling of malformed Expect headers, the page produced by the cross-site scripting attack will only be returned after a timeout expires (2-5 minutes by default) if not first canceled by the user. Users of httpd should update to these erratum packages, which contain a backported patch to correct these issues.
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