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Gentoo Linux Security Advisory                           GLSA 202012-21
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                                            https://security.gentoo.org/
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  Severity: Low
     Title: Mozilla Network Security Service (NSS): Denial of service
      Date: December 23, 2020
      Bugs: #750254
        ID: 202012-21

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Synopsis
========

A vulnerability in NSS might allow remote attackers to cause a Denial
of Service condition.

Background
==========

The Mozilla Network Security Service (NSS) is a library implementing
security features like SSL v.2/v.3, TLS, PKCS #5, PKCS #7, PKCS #11,
PKCS #12, S/MIME and X.509 certificates.

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

     -------------------------------------------------------------------
      Package              /     Vulnerable     /            Unaffected
     -------------------------------------------------------------------
   1  dev-libs/nss                  < 3.58                     >= 3.58

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

A flaw was found in the way Mozilla Network Security Service (NSS)
handled CCS (ChangeCipherSpec) messages in TLS 1.3.

Impact
======

A remote attacker could send multiple crafted CSS messages in row after
ClientHello message to a server application linked against NSS library,
possibly resulting in a Denial of Service condition.

Workaround
==========

Disable TLS 1.3 protocol.

Resolution
==========

All NSS users should upgrade to the latest version:

   # emerge --sync
   # emerge --ask --oneshot --verbose ">=dev-libs/nss-3.58"

References
==========

[ 1 ] CVE-2020-25648
       https://nvd.nist.gov/vuln/detail/CVE-2020-25648

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

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

  https://security.gentoo.org/glsa/202012-21

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