A ksh security update has been released for Debian GNU/Linux 9 LTS to address a flaw in the way it evaluates certain environment variables.

DLA 2284-1: ksh security update

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Debian LTS Advisory DLA-2284-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Brian May
July 21, 2020   https://wiki.debian.org/LTS
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Package : ksh
Version : 93u+20120801-3.1+deb9u1
CVE ID : CVE-2019-14868

A flaw was found in the way it evaluates certain
environment variables. An attacker could use this
flaw to override or bypass environment restrictions
to execute shell commands. Services and
applications that allow remote unauthenticated
attackers to provide one of those environment
variables could allow them to exploit this issue
remotely.

For Debian 9 stretch, this problem has been fixed in version
93u+20120801-3.1+deb9u1.

We recommend that you upgrade your ksh packages.

For the detailed security status of ksh please refer to
its security tracker page at:
  https://security-tracker.debian.org/tracker/ksh

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at:   https://wiki.debian.org/LTS