(RHSA-2009:1580) Moderate: httpd security update

The Apache HTTP Server is a popular Web server.

A flaw was found in the way the TLS/SSL (Transport Layer Security/Secure
Sockets Layer) protocols handle session renegotiation. A man-in-the-middle
attacker could use this flaw to prefix arbitrary plain text to a client’s
session (for example, an HTTPS connection to a website). This could force
the server to process an attacker’s request as if authenticated using the
victim’s credentials. This update partially mitigates this flaw for SSL
sessions to HTTP servers using mod_ssl by rejecting client-requested
renegotiation. (CVE-2009-3555)

Note: This update does not fully resolve the issue for HTTPS servers. An
attack is still possible in configurations that require a server-initiated
renegotiation. Refer to the following Knowledgebase article for further
information: http://kbase.redhat.com/faq/docs/DOC-20491

A denial of service flaw was found in the Apache mod_deflate module. This
module continued to compress large files until compression was complete,
even if the network connection that requested the content was closed before
compression completed. This would cause mod_deflate to consume large
amounts of CPU if mod_deflate was enabled for a large file. (CVE-2009-1891)

A NULL pointer dereference flaw was found in the Apache mod_proxy_ftp
module. A malicious FTP server to which requests are being proxied could
use this flaw to crash an httpd child process via a malformed reply to the
EPSV or PASV commands, resulting in a limited denial of service.
(CVE-2009-3094)

A second flaw was found in the Apache mod_proxy_ftp module. In a reverse
proxy configuration, a remote attacker could use this flaw to bypass
intended access restrictions by creating a carefully-crafted HTTP
Authorization header, allowing the attacker to send arbitrary commands to
the FTP server. (CVE-2009-3095)

All httpd users should upgrade to these updated packages, which contain
backported patches to correct these issues. After installing the updated
packages, the httpd daemon must be restarted for the update to take effect.