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Category:   Application (Web Server/CGI)  >   Apache Tomcat Vendors:   Apache Software Foundation
(Red Hat Issues Fix) Apache Tomcat Connection Processing Bug Lets Remote Users Deny Service
SecurityTracker Alert ID:  1028174
SecurityTracker URL:
CVE Reference:   CVE-2012-4534   (Links to External Site)
Date:  Feb 20 2013
Impact:   Denial of service via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 6.0.0 to 6.0.35, 7.0.0 to 7.0.27
Description:   A vulnerability was reported in Apache Tomcat. A remote user can cause denial of service conditions.

A remote user can break the connection while reading the response to cause the target system to enter an infinite loop.

Systems using the NIO connector with sendfile and HTTPS enabled are affected.

Arun Neelicattu of the Red Hat Security Response Team reported this vulnerability.

Impact:   A remote user can the system to enter an infinite loop.
Solution:   Red Hat has issued 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, 6

Message History:   This archive entry is a follow-up to the message listed below.
Dec 5 2012 Apache Tomcat Connection Processing Bug Lets Remote Users Deny Service

 Source Message Contents

Subject:  [RHSA-2013:0266-01] Moderate: tomcat6 security update

Hash: SHA1

                   Red Hat Security Advisory

Synopsis:          Moderate: tomcat6 security update
Advisory ID:       RHSA-2013:0266-01
Product:           JBoss Enterprise Web Server
Advisory URL:
Issue date:        2013-02-19
CVE Names:         CVE-2012-2733 CVE-2012-4431 CVE-2012-4534 
                   CVE-2012-5885 CVE-2012-5886 CVE-2012-5887 

1. Summary:

Updated tomcat6 packages that fix multiple security issues are now
available for JBoss Enterprise Web Server 2.0.0 for Red Hat Enterprise
Linux 5 and 6.

The Red Hat Security Response Team has rated this update as having moderate
security impact. Common Vulnerability Scoring System (CVSS) base scores,
which give detailed severity ratings, are available for each vulnerability
from the CVE links in the References section.

2. Relevant releases/architectures:

JBoss Enterprise Web Server 2 for RHEL 5 Server - noarch
JBoss Enterprise Web Server 2 for RHEL 6 Server - noarch

3. Description:

Apache Tomcat is a servlet container.

It was found that sending a request without a session identifier to a
protected resource could bypass the Cross-Site Request Forgery (CSRF)
prevention filter. A remote attacker could use this flaw to perform
CSRF attacks against applications that rely on the CSRF prevention filter
and do not contain internal mitigation for CSRF. (CVE-2012-4431)

A flaw was found in the way Tomcat handled sendfile operations when using
the HTTP NIO (Non-Blocking I/O) connector and HTTPS. A remote attacker
could use this flaw to cause a denial of service (infinite loop). The HTTP
NIO connector is used by default in JBoss Enterprise Web Server. The Apache
Portable Runtime (APR) connector from the Tomcat Native library was not
affected by this flaw. (CVE-2012-4534)

Multiple weaknesses were found in the Tomcat DIGEST authentication
implementation, effectively reducing the security normally provided by
DIGEST authentication. A remote attacker could use these flaws to perform
replay attacks in some circumstances. (CVE-2012-5885, CVE-2012-5886,

A denial of service flaw was found in the way the Tomcat HTTP NIO connector
enforced limits on the permitted size of request headers. A remote attacker
could use this flaw to trigger an OutOfMemoryError by sending a
specially-crafted request with very large headers. The HTTP NIO connector
is used by default in JBoss Enterprise Web Server. The APR connector from
the Tomcat Native library was not affected by this flaw. (CVE-2012-2733)

Warning: Before applying the update, back up your existing JBoss Enterprise
Web Server installation (including all applications and configuration

Users of Tomcat should upgrade to these updated packages, which resolve
these issues. Tomcat must be restarted for this update to take effect.

4. Solution:

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

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

5. Bugs fixed (

873664 - CVE-2012-5885 CVE-2012-5886 CVE-2012-5887 tomcat: three DIGEST authentication implementation issues
873695 - CVE-2012-2733 tomcat: HTTP NIO connector OOM DoS via a request with large headers
883636 - CVE-2012-4431 Tomcat/JBoss Web - Bypass of CSRF prevention filter
883637 - CVE-2012-4534 Tomcat - Denial Of Service when using NIO+SSL+sendfile

6. Package List:

JBoss Enterprise Web Server 2 for RHEL 5 Server:



JBoss Enterprise Web Server 2 for RHEL 6 Server:



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 2013 Red Hat, Inc.
Version: GnuPG v1.4.4 (GNU/Linux)


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