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CERT Coordination Center

GnuTLS Client Hello repeat Denial of Service

Vulnerability Note VU#252626

Original Release Date: 2008-05-29 | Last Revised: 2008-05-29


A vulnerability exists in GnuTLS that may allow a remote attacker to cause a denial of service.


GnuTLS contains a vulnerability in gnults-serv that may result in a denial of service when handling a specially crafted TLS packet that contains multiple Client Hello messages. According to CERT-FI Vulnerability Advisory on GnuTLS:

    The program reads the first Client Hello and then proceeds to send Server Hello, Certificate, Certificate Request and Server Hello Done messages. After sending these, it apperently reads next Client Hello from the message sent earlier and crashes to segmentation fault caused by null pointer.

Note that this issue may affect GnuTLS versions prior to 2.2.5 and also affects version 2.3.0.


A remote, unauthorized attacker may be able to cause a denial of service.


Upgrade or Apply Patch
GnuTLS has issued an upgrade and a patch to address this issue. See GnuTLS Security Advisory SA-2008-01 for more information. GnuTLS is included in various Linux and UNIX distributions. Please consult the relevant documentation of your distribution to obtain the appropriate updates.

Vendor Information


GnuTLS Affected

Updated:  May 29, 2008



Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


Refer to GnuTLS Security Advisory SA-2008-01 for more information.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

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This issue was reported in GnuTLS Security Advisory SA-2008-01. GnuTLS credits Ossi Herrala and Jukka Taimisto from the CROSS project at Codenomicon Ltd. for reporting this issue.

This document was written by Chris Taschner.

Other Information

CVE IDs: CVE-2008-1949
Severity Metric: 9.19
Date Public: 2008-05-19
Date First Published: 2008-05-29
Date Last Updated: 2008-05-29 15:45 UTC
Document Revision: 15

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