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Category:   Application (Web Server/CGI)  >   Apache mod_proxy Vendors:   Apache Software Foundation
(Red Hat Issues Fix) Apache mod_proxy stream_reqbody_cl() Infinite Loop Lets Remote Users Deny Service
SecurityTracker Alert ID:  1022552
SecurityTracker URL:
CVE Reference:   CVE-2009-1890   (Links to External Site)
Date:  Jul 14 2009
Impact:   Denial of service via network
Fix Available:  Yes  Vendor Confirmed:  Yes  

Description:   A vulnerability was reported in Apache mod_proxy. A remote user can cause denial of service conditions.

A remote user can send specially crafted Content-Length value to cause the stream_reqbody_cl() function in 'modules/proxy/mod_proxy_http.c' to enter an infinite loop.

Impact:   A remote user can cause the target service to enter an infinite loop.
Solution:   Red Hat has released a fix.

The Red Hat advisory is available at:

Vendor URL: (Links to External Site)
Cause:   State error
Underlying OS:  Linux (Red Hat Enterprise)
Underlying OS Comments:  5

Message History:   This archive entry is a follow-up to the message listed below.
Jul 3 2009 Apache mod_proxy stream_reqbody_cl() Infinite Loop Lets Remote Users Deny Service

 Source Message Contents

Subject:  [RHSA-2009:1156-01] Important: httpd security update

Hash: SHA1

                   Red Hat Security Advisory

Synopsis:          Important: httpd security update
Advisory ID:       RHSA-2009:1156-01
Product:           Red Hat Application Stack
Advisory URL:
Issue date:        2009-07-14
CVE Names:         CVE-2009-1195 CVE-2009-1890 CVE-2009-1891 

1. Summary:

Updated httpd packages that fix multiple security issues are now available
for Red Hat Application Stack v2.

This update has been rated as having important security impact by the Red
Hat Security Response Team.

2. Relevant releases/architectures:

Red Hat Application Stack v2 for Enterprise Linux (v.5) - i386, x86_64

3. Description:

The Apache HTTP Server is a popular Web server.

A denial of service flaw was found in the Apache mod_proxy module when it
was used as a reverse proxy. A remote attacker could use this flaw to force
a proxy process to consume large amounts of CPU time. (CVE-2009-1890)

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 flaw was found in the handling of the "Options" and "AllowOverride"
directives used by the Apache HTTP Server. In configurations using the
"AllowOverride" directive with certain "Options=" arguments, local users
were not restricted from executing commands from a Server-Side-Include
script as intended. (CVE-2009-1195)

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.

4. Solution:

Before applying this update, make sure that all previously-released
errata relevant to your system have been applied.

This update is available via Red Hat Network.  Details on how to use
the Red Hat Network to apply this update are available at

5. Bugs fixed (

489436 - CVE-2009-1195 AllowOverride Options=IncludesNoExec allows Options Includes
509125 - CVE-2009-1891 httpd: possible temporary DoS (CPU consumption) in mod_deflate
509375 - CVE-2009-1890 httpd: mod_proxy reverse proxy DoS (infinite loop)

6. Package List:

Red Hat Application Stack v2 for Enterprise Linux (v.5):




These packages are GPG signed by Red Hat for security.  Our key and 
details on how to verify the signature are available from

7. References:

8. Contact:

The Red Hat security contact is <>.  More contact
details at

Copyright 2009 Red Hat, Inc.
Version: GnuPG v1.4.4 (GNU/Linux)


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