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7.75. httpd

Updated httpd packages that fix one security issue, several bugs, and add one enhancement are now available for Red Hat Enterprise Linux 6.
Red Hat Product Security has rated this update as having Low security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.
The httpd packages provide the Apache HTTP Server, a powerful, efficient, and extensible web server.

Security Fix

A flaw was found in the way httpd handled HTTP Trailer headers when processing requests using chunked encoding. A malicious client could use Trailer headers to set additional HTTP headers after header processing was performed by other modules. This could, for example, lead to a bypass of header restrictions defined with mod_headers.

Bug Fixes

The order of mod_proxy workers was not checked when httpd configuration was reloaded. When mod_proxy workers were removed, added, or their order was changed, their parameters and scores could become mixed. The order of mod_proxy workers has been made internally consistent during configuration reload.
The local host certificate created during firstboot contained CA extensions, which caused the httpd service to return warning messages. This has been addressed by local host certificates being generated with the "-extensions v3_req" option.
The default mod_ssl configuration no longer enables support for SSL cipher suites using the single DES, IDEA, or SEED encryption algorithms.
The apachectl script did not take into account the HTTPD_LANG variable set in the /etc/sysconfig/httpd file during graceful restarts. Consequently, httpd did not use a changed value of HTTPD_LANG when the daemon was restarted gracefully. The script has been fixed to handle the HTTPD_LANG variable correctly.
The mod_deflate module failed to check the original file size while extracting files larger than 4 GB, making it impossible to extract large files. Now, mod_deflate checks the original file size properly according to RFC1952, and it is able to decompress files larger than 4 GB.
The httpd service did not check configuration before restart. When a configuration contained an error, an attempt to restart httpd gracefully failed. Now, httpd checks configuration before restart and if the configuration is in an inconsistent state, an error message is printed, httpd is not stopped and a restart is not performed.
The SSL_CLIENT_VERIFY environment variable was incorrectly handled when the "SSLVerifyClient optional_no_ca" and "SSLSessionCache" options were used. When an SSL session was resumed, the SSL_CLIENT_VERIFY value was set to "SUCCESS" instead of the previously set "GENEROUS". SSL_CLIENT_VERIFY is now correctly set to GENEROUS in this scenario.
The ab utility did not correctly handle situations when an SSL connection was closed after some data had already been read. As a consequence, ab did not work correctly with SSL servers and printed "SSL read failed" error messages. With this update, ab works as expected with HTTPS servers.
When a client presented a revoked certificate, log entries were created only at the debug level. The log level of messages regarding a revoked certificate has been increased to INFO, and administrators are now properly informed of this situation.


A mod_proxy worker can now be set into drain mode (N) using the balancer-manager web interface or using the httpd configuration file. A worker in drain mode accepts only existing sticky sessions destined for itself and ignores all other requests. The worker waits until all clients currently connected to this worker complete their work before the worker is stopped. As a result, drain mode enables to perform maintenance on a worker without affecting clients.
Users of httpd are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add this enhancement. After installing the updated packages, the httpd service will be restarted automatically.