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Gentoo Linux Security Advisory                           GLSA 202004-08
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                                           https://security.gentoo.org/
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 Severity: Low
    Title: libssh: Denial of Service
     Date: April 10, 2020
     Bugs: #716788
       ID: 202004-08

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Synopsis
========

A vulnerability in libssh could allow a remote attacker to cause a
Denial of Service condition.

Background
==========

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

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

    -------------------------------------------------------------------
     Package              /     Vulnerable     /            Unaffected
    -------------------------------------------------------------------
  1  net-libs/libssh              < 0.9.4                    >= 0.9.4

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

It was discovered that libssh could crash when AES-CTR ciphers are
used.

Impact
======

A remote attacker running a malicious client or server could possibly
crash the counterpart implemented with libssh and cause a Denial of
Service condition.

Workaround
==========

Disable AES-CTR ciphers. If you implement a server using libssh it is
recommended to use a prefork model so each session runs in an own
process.

Resolution
==========

All libssh users should upgrade to the latest version:

  # emerge --sync
  # emerge --ask --oneshot --verbose ">=net-libs/libssh-0.9.4"

References
==========

[ 1 ] CVE-2020-1730
      https://nvd.nist.gov/vuln/detail/CVE-2020-1730

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

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

 https://security.gentoo.org/glsa/202004-08

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 2020 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