Scientific Linux Security Update : httpd on SL6.x i386/x86_64

Medium Nessus Plugin ID 85196


The remote Scientific Linux host is missing one or more security updates.


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.

This update also fixes the following bugs :

- 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.

In addition, this update adds the following enhancement :

- 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.

After installing the updated packages, the httpd service will be restarted automatically.


Update the affected packages.

See Also

Plugin Details

Severity: Medium

ID: 85196

File Name: sl_20150722_httpd_on_SL6_x.nasl

Version: $Revision: 2.1 $

Type: local

Agent: unix

Published: 2015/08/04

Modified: 2015/08/04

Dependencies: 12634

Risk Information

Risk Factor: Medium


Base Score: 5

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N

Vulnerability Information

CPE: x-cpe:/o:fermilab:scientific_linux

Required KB Items: Host/local_checks_enabled, Host/cpu, Host/RedHat/release, Host/RedHat/rpm-list

Patch Publication Date: 2015/07/22

Reference Information

CVE: CVE-2013-5704