Etienne Stalmans discovered that unsquashfs in squashfs-tools, the tools
to create and extract Squashfs filesystems, does not validate filenames
for traversal outside of the destination 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+deb10u1.
For the stable distribution (bullseye), this problem has been fixed in
We recommend that you upgrade your squashfs-tools packages.