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Gentoo Linux Security Advisory                           GLSA 201606-12
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                                           https://security.gentoo.org/
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 Severity: Normal
    Title: libssh and libssh2: Multiple vulnerabilities
     Date: June 26, 2016
     Bugs: #533366, #575474, #575484
       ID: 201606-12

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Synopsis
========

Multiple vulnerabilities have been found in libssh and libssh2, the
worst of which allows remote attackers to cause Denial of Service.

Background
==========

libssh is a mulitplatform C library implementing the SSHv2 and SSHv1
protocol on client and server side.

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

    -------------------------------------------------------------------
     Package              /     Vulnerable     /            Unaffected
    -------------------------------------------------------------------
  1  net-libs/libssh              < 0.7.3                    >= 0.7.3 
  2  net-libs/libssh2             < 1.7.0                    >= 1.7.0 
    -------------------------------------------------------------------
     2 affected packages

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

libssh and libssh2 both have a bits/bytes confusion bug and generate an
abnormaly short ephemeral secret for the diffie-hellman-group1 and
diffie-hellman-group14 key exchange methods. The resulting secret is
128 bits long, instead of the recommended sizes of 1024 and 2048 bits
respectively.

Additionally, a double free on dangling pointers in initial key
exchange packets within libssh could leave dangling pointers in the
session crypto structures. It is possible to send a malicious kexinit
package to eventually cause a server to do a double-free before this
fix. This could be used for a Denial of Service attack.

Impact
======

Remote attackers may gain access to confidential information due to the
short keysize generated by libssh and libssh2, or cause a Denial of
Service condition.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All libssh users should upgrade to the latest version:

  # emerge --sync
  # emerge --ask --oneshot --verbose ">=net-libs/libssh-0.7.3"

All libssh2 users should upgrade to the latest version:

  # emerge --sync
  # emerge --ask --oneshot --verbose ">=net-libs/libssh2-1.7.0"

References
==========

[ 1 ] CVE-2014-8132
      https://nvd.nist.gov/nvd.cfm?cvename=CVE-2014-8132
[ 2 ] CVE-2016-0739
      https://nvd.nist.gov/nvd.cfm?cvename=CVE-2016-0739
[ 3 ] CVE-2016-0787
      https://nvd.nist.gov/nvd.cfm?cvename=CVE-2016-0787

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

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

 https://security.gentoo.org/glsa/201606-12

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@gentoo.org or alternatively, you may file a bug at
https://bugs.gentoo.org.

License
=======

Copyright 2016 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.

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