Apache mod_proxy_ajp HTTP Processing Error Lets Remote Users Deny Service
SecurityTracker Alert ID: 1026054|
SecurityTracker URL: http://securitytracker.com/id/1026054
(Links to External Site)
Date: Sep 15 2011
Denial of service via network|
Fix Available: Yes Vendor Confirmed: Yes |
Version(s): prior to 2.2.21|
A vulnerability was reported in Apache mod_proxy_ajp. A remote user can cause denial of service conditions.|
When mod_proxy_ajp is used together with mod_proxy_balancer, a remote user can send specially crafted HTTP requests to place the backend server in an error state until the retry timeout expires.
A remote user can cause the backend server to remain in an error state until the retry timeout expires.|
The vendor has issued a fix (2.2.21).|
Vendor URL: httpd.apache.org/ (Links to External Site)
Input validation error, State error|
|Underlying OS: Linux (Any), UNIX (Any), Windows (Any)|
This archive entry has one or more follow-up message(s) listed below.|
Source Message Contents
Subject: Apache HTTP Server 2.2.21 Released|
The Apache Software Foundation and the Apache HTTP Server Project are
pleased to announce the release of version 2.2.21 of the Apache HTTP
Server ("Apache"). This version of Apache is principally a security
and bug fix release:
* SECURITY: CVE-2011-3348 (cve.mitre.org)
mod_proxy_ajp when combined with mod_proxy_balancer: Prevents
unrecognized HTTP methods from marking ajp: balancer members
in an error state, avoiding denial of service.
* SECURITY: CVE-2011-3192 (cve.mitre.org)
core: Further fixes to the handling of byte-range requests to use
less memory, to avoid denial of service. This patch includes fixes
to the patch introduced in release 2.2.20 for protocol compliance,
as well as the MaxRanges directive.
Note the further advisories on the state of CVE-2011-3192 will no longer
be broadcast, but will be kept up to date at;
We consider this release to be the best version of Apache available, and
encourage users of all prior versions to upgrade.
Apache HTTP Server 2.2.21 is available for download from:
Please see the CHANGES_2.2 file, linked from the download page, for a
full list of changes. A condensed list, CHANGES_2.2.21 provides the
complete list of changes since 2.2.19. A summary of all of the security
vulnerabilities addressed in this and earlier releases is available:
This release includes the Apache Portable Runtime (APR) version 1.4.5
and APR Utility Library (APR-util) version 1.3.12, bundled with the tar
and zip distributions. The APR libraries libapr and libaprutil (and
on Win32, libapriconv version 1.2.1) must all be updated to ensure
binary compatibility and address many known security and platform bugs.
Apache 2.2 offers numerous enhancements, improvements, and performance
boosts over the 2.0 codebase. For an overview of new features
introduced since 2.0 please see:
This release builds on and extends the Apache 2.0 API. Modules written
for Apache 2.0 will need to be recompiled in order to run with Apache
2.2, and require minimal or no source code changes.
When upgrading or installing this version of Apache, please bear in mind
that if you intend to use Apache with one of the threaded MPMs (other
than the Prefork MPM), you must ensure that any modules you will be
using (and the libraries they depend on) are thread-safe.