A squashfs-tools security update has been released for Debian GNU/Linux 10 and 11 to address an issue where squashfs-tools does not check for duplicate filenames within a directory.

DSA 4987-1: squashfs-tools security update

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Debian Security Advisory DSA-4987-1 security@debian.org
  https://www.debian.org/security/ Salvatore Bonaccorso
October 15, 2021   https://www.debian.org/security/faq
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Package : squashfs-tools
CVE ID : CVE-2021-41072
Debian Bug : 994262

Richard Weinberger reported that unsquashfs in squashfs-tools, the tools
to create and extract Squashfs filesystems, does not check for duplicate
filenames within a directory. An attacker can take advantage of this
flaw for writing to arbitrary files to the filesystem if a malformed
Squashfs image is processed.

For the oldstable distribution (buster), this problem has been fixed
in version 1:4.3-12+deb10u2.

For the stable distribution (bullseye), this problem has been fixed in
version 1:4.4-2+deb11u2.

We recommend that you upgrade your squashfs-tools packages.

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

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