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