An apng2gif security update has been released for Debian GNU/Linux 9 LTS to address several vulnerabilities.

DLA 2911-1: apng2gif security update

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Debian LTS Advisory DLA-2911-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Markus Koschany
February 04, 2022   https://wiki.debian.org/LTS
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Package : apng2gif
Version : 1.8-0.1~deb9u1
CVE ID : CVE-2017-6960 CVE-2017-6961 CVE-2017-6962
Debian Bug : 854447

Several vulnerabilities have been discovered in apng2gif, a tool for converting
APNG images to animated GIF format. Improper sanitization of user input can
result in denial of service (application crash) or possible execution of
arbitrary code if a malformed image file is processed.

For Debian 9 stretch, these problems have been fixed in version
1.8-0.1~deb9u1.

We recommend that you upgrade your apng2gif packages.

For the detailed security status of apng2gif please refer to
its security tracker page at:
  https://security-tracker.debian.org/tracker/apng2gif

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