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Ubuntu Security Notice USN-5057-1
August 31, 2021

squashfs-tools vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 21.04
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

squashfs-tools could be made to overwrite files.

Software Description:
- squashfs-tools: Tools to create and modify squashfs filesystems

Details:

Etienne Stalmans discovered that Squashfs-Tools mishandled certain malformed SQUASHFS files. An attacker could use this vulnerability to write arbitrary files to the filesystem.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 21.04:
  squashfs-tools                  1:4.4-2ubuntu0.1

Ubuntu 20.04 LTS:
  squashfs-tools                  1:4.4-1ubuntu0.1

Ubuntu 18.04 LTS:
  squashfs-tools                  1:4.3-6ubuntu0.18.04.3

In general, a standard system update will make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-5057-1
  CVE-2021-40153

Package Information:
  https://launchpad.net/ubuntu/+source/squashfs-tools/1:4.4-2ubuntu0.1
  https://launchpad.net/ubuntu/+source/squashfs-tools/1:4.4-1ubuntu0.1
  https://launchpad.net/ubuntu/+source/squashfs-tools/1:4.3-6ubuntu0.18.04.3