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Gentoo Linux Security Advisory                           GLSA 202105-38
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                                            https://security.gentoo.org/
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  Severity: High
     Title: nginx: Remote code execution
      Date: May 26, 2021
      Bugs: #792087
        ID: 202105-38

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Synopsis
=======
A vulnerability in nginx could lead to remote code execution.

Background
=========
nginx is a robust, small, and high performance HTTP and reverse proxy
server.

Affected packages
================
     -------------------------------------------------------------------
      Package              /     Vulnerable     /            Unaffected
     -------------------------------------------------------------------
   1  www-servers/nginx            < 1.21.0                >= 1.20.1:0
                                                    >= 1.21.0:mainline

Description
==========
It was discovered that nginx did not properly handle DNS responses when
"resolver" directive is used.

Impact
=====
A remote attacker, able to provide DNS responses to a nginx instance,
could cause the execution of arbitrary code with the privileges of the
process or a Denial of Service condition.

Workaround
=========
There is no known workaround at this time.

Resolution
=========
All nginx users should upgrade to the latest version:

   # emerge --sync
   # emerge --ask --oneshot --verbose ">=www-servers/nginx-1.20.1"

All nginx mainline users should upgrade to the latest version:

   # emerge --sync
   # emerge --ask --oneshot -v ">=www-servers/nginx-1.21.0:mainline"

References
=========
[ 1 ] CVE-2021-23017
       https://nvd.nist.gov/vuln/detail/CVE-2021-23017

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

  https://security.gentoo.org/glsa/202105-38

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 2021 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/