GnuTLS Server Name extension Denial of Service

Overview

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

Description

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

The problem occurs when gnutls-serv receives Client Hello message which contains Server name extension where the length of the server name list is set to 18 and the data of the server name list consists of 18 zero octets. After receiving this Client Hello message gnutls-serv continues to function normally, but crashes after Finished messages when it tries to pack the session data in function pack_security_parameters() (in lib/gnutls_session_pack.c).
Note that this issue may affect GnuTLS versions prior to 2.2.5 and also affects version 2.3.0.

Impact

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

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Solution

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.

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Vendor Information

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GnuTLS __ Affected

Updated: May 29, 2008

Status

Affected

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.

Addendum

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](<mailto:[email protected]?Subject=VU%23111034 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://www.cert.fi/haavoittuvuudet/advisory-gnutls.html&gt;
• <http://lists.gnu.org/archive/html/gnutls-devel/2008-05/msg00060.html&gt;
• <http://secunia.com/advisories/30287/&gt;
• <http://secunia.com/advisories/30330/&gt;

Acknowledgements

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-2008-1950
Severity Metric:	9.19 Date Public: