[ GLSA 200609-15 ] GnuTLS: RSA Signature Forgery

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Gentoo Linux Security Advisory GLSA 200609-15
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                                            http://security.gentoo.org/
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  Severity: Normal
     Title: GnuTLS: RSA Signature Forgery
      Date: September 26, 2006
      Bugs: #147682
        ID: 200609-15

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Synopsis
========

GnuTLS fails to handle excess data which could allow an attacker to
forge a PKCS #1 v1.5 signature.

Background
==========

GnuTLS is an implementation of SSL 3.0 and TLS 1.0.

Affected packages
=================

    -------------------------------------------------------------------
     Package / Vulnerable / Unaffected
    -------------------------------------------------------------------
  1 net-libs/gnutls < 1.4.4 >= 1.4.4

Description
===========

verify.c fails to properly handle excess data in
digestAlgorithm.parameters field while generating a hash when using an
RSA key with exponent 3. RSA keys that use exponent 3 are commonplace.

Impact
======

Remote attackers could forge PKCS #1 v1.5 signatures that are signed
with an RSA key, preventing GnuTLS from correctly verifying X.509 and
other certificates that use PKCS.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All GnuTLS users should update both packages:

    # emerge --sync
    # emerge --update --ask --verbose ">=net-libs/gnutls-1.4.4"

References
==========

  [ 1 ] CVE-2006-4790
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4790

Availability
============

This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

  http://security.gentoo.org/glsa/glsa-200609-15.xml

Concerns?
=========

Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users machines is of utmost
importance to us. Any security concerns should be addressed to
security_at_gentoo.org or alternatively, you may file a bug at
http://bugs.gentoo.org.

License
=======

Copyright 2006 Gentoo Foundation, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

http://creativecommons.org/licenses/by-sa/2.5

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