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Gentoo Linux Security Advisory                           GLSA 202105-02
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                                            https://security.gentoo.org/
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  Severity: Low
     Title: stunnel: Improper certificate validation
      Date: May 26, 2021
      Bugs: #772146
        ID: 202105-02

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Synopsis
========

Stunnel was not properly verifying TLS certificates, possibly allowing
an integrity/confidentiality compromise.

Background
==========

The stunnel program is designed to work as an SSL/TLS encryption
wrapper between a client and a local or remote server.

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

     -------------------------------------------------------------------
      Package              /     Vulnerable     /            Unaffected
     -------------------------------------------------------------------
   1  net-misc/stunnel              < 5.58                     >= 5.58

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

It was discovered that stunnel did not correctly verified the client
certificate when options "redirect" and "verifyChain" are used.

Impact
======

A remote attacker could send a specially crafted certificate, possibly
resulting in a breach of integrity or confidentiality.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All stunnel users should upgrade to the latest version:

   # emerge --sync
   # emerge --ask --oneshot --verbose ">=net-misc/stunnel-5.58"

References
==========

[ 1 ] CVE-2021-20230
       https://nvd.nist.gov/vuln/detail/CVE-2021-20230

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

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

  https://security.gentoo.org/glsa/202105-02

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 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