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CVE-2009-0033: Apache Tomcat denial of service vulnerability

Severity: important

Vendor:
The Apache Software Foundation

Versions Affected:
Tomcat 6.0.0 to 6.0.18
Tomcat 5.5.0 to 5.5.27
Tomcat 4.1.0 to 4.1.39

The unsupported Tomcat 3.x, 4.0.x and 5.0.x versions may be also affected.

Description:
If Tomcat receives a request with invalid headers via the Java AJP
connector, it does not return an error and instead closes the AJP
connection. In case this connector is member of a mod_jk load balancing
worker, this member will be put into an error state and will be blocked
from use for approximately one minute. Thus the behaviour can be used
for a denial of service attack using a carefully crafted request.

Mitigation:
6.0.x users should do one of the following:
 - upgrade to 6.0.20
- apply this patch http://svn.apache.org/viewvc?rev=742915&view=rev 
5.5.x users should do one of the following:
 - upgrade to 5.5.28 when released
- apply this patch http://svn.apache.org/viewvc?rev=781362&view=rev 
4.1.x users should do one of the following:
 - upgrade to 4.1.40 when released
- apply this patch http://svn.apache.org/viewvc?rev=781362&view=rev 

Example:
GET /servlets-examples/ HTTP/1.1
Host: localhost:x

Credit:
This issue was discovered by Yoshihito Fukuyama.

References:
http://tomcat.apache.org/security.html 
http://tomcat.apache.org/security-6.html 
http://tomcat.apache.org/security-5.html 
http://tomcat.apache.org/security-4.html 

The Apache Tomcat Security Team


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