[ GLSA 202012-06 ] Linux-PAM: Authentication bypass

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Gentoo Linux Security Advisory                           GLSA 202012-06
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                                            https://security.gentoo.org/
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  Severity: Normal
     Title: Linux-PAM: Authentication bypass
      Date: December 07, 2020
      Bugs: #756361
        ID: 202012-06

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Synopsis
========

A vulnerability has been found in Linux-PAM, allowing attackers to
bypass the authentication process.

Background
==========

Linux-PAM (Pluggable Authentication Modules) is an architecture
allowing the separation of the development of privilege granting
software from the development of secure and appropriate authentication
schemes.

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

     -------------------------------------------------------------------
      Package              /     Vulnerable     /            Unaffected
     -------------------------------------------------------------------
   1  sys-libs/pam                 < 1.5.1                    >= 1.5.1

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

A flaw was found in Linux-Pam in the way it handle empty passwords for
non-existing users.

Impact
======

A remote attacker, who only needs to know a non-existing username,
could bypass security restrictions and authenticate as root user.

Workaround
==========

Ensure that root account is protected by a non-empty password.

Resolution
==========

All Linux-PAM users should upgrade to the latest version:

   # emerge --sync
   # emerge --ask --oneshot --verbose ">=sys-libs/pam-1.5.1"

References
==========

[ 1 ] CVE-2020-27780
       https://nvd.nist.gov/vuln/detail/CVE-2020-27780

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

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

  https://security.gentoo.org/glsa/202012-06

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
[email protected] 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