A pngcheck security update has been released for Debian GNU/Linux 9 LTS.

DLA 3032-1: pngcheck security update

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Debian LTS Advisory DLA-3032-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Markus Koschany
May 29, 2022   https://wiki.debian.org/LTS
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Package : pngcheck
Version : 2.3.0-7+deb9u1
CVE ID : CVE-2020-27818
Debian Bug : 976350

A flaw was found in the check_chunk_name() function of pngcheck, a tool to 
verify the integrity of PNG, JNG and MNG files. This flaw allows an attacker
who can pass a malicious file to be processed by pngcheck to cause a temporary
denial of service.

For Debian 9 stretch, this problem has been fixed in version
2.3.0-7+deb9u1.

We recommend that you upgrade your pngcheck packages.

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

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