CVE-2021-40153

Name: CVE-2021-40153
Creator: NVD / NIST
Published: 2021-08-27T15:15:09.657+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.1/10EPSS 2.50%

Last modified Jun 17, 2026

CVE-2021-40153 is a high-severity vulnerability rated 8.1/10 on the CVSS scale. squashfs_opendir in unsquash-1.c in Squashfs-Tools 4.5 stores the filename in the directory entry; this is then used by unsquashfs to create the new file during the unsquash. The filename is not validated for traversal outside of the destination directory, and thus allows writing to locations outside of the destination.. EPSS estimates a 2.50% chance of exploitation in the next 30 days.

Description

squashfs_opendir in unsquash-1.c in Squashfs-Tools 4.5 stores the filename in the directory entry; this is then used by unsquashfs to create the new file during the unsquash. The filename is not validated for traversal outside of the destination directory, and thus allows writing to locations outside of the destination.

Metrics

CVSS 3.1

8.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H

EPSS Probability

2.50%

82.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-22

Affected Software

Vendor	Product	Versions
Squashfs-Tools Project	Squashfs-Tools	4.5
Fedoraproject	Fedora	34
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0
Redhat	Enterprise Linux	7.0
Redhat	Enterprise Linux	8.0
Fedoraproject	Fedora	33

References

https://bugs.launchpad.net/ubuntu/+source/squashfs-tools/+bug/1941790Third Party Advisory
https://github.com/plougher/squashfs-tools/commit/79b5a555058eef4e1e7ff220c344d39f8cd09646Patch, Third Party Advisory
https://github.com/plougher/squashfs-tools/issues/72Exploit, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/08/msg00030.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GSMRKVJMJFX3MB7D3PXJSYY3TLZROE5S/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RAOZ4BKWAC4Y3U2K5MMW3S77HWWXHQDL/
https://security.gentoo.org/glsa/202305-29
https://www.debian.org/security/2021/dsa-4967Third Party Advisory
https://bugs.launchpad.net/ubuntu/+source/squashfs-tools/+bug/1941790Third Party Advisory
https://github.com/plougher/squashfs-tools/commit/79b5a555058eef4e1e7ff220c344d39f8cd09646Patch, Third Party Advisory
https://github.com/plougher/squashfs-tools/issues/72Exploit, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/08/msg00030.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GSMRKVJMJFX3MB7D3PXJSYY3TLZROE5S/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RAOZ4BKWAC4Y3U2K5MMW3S77HWWXHQDL/
https://security.gentoo.org/glsa/202305-29
https://www.debian.org/security/2021/dsa-4967Third Party Advisory

Timeline

Published: Aug 27, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-40153?

How severe is CVE-2021-40153?

CVE-2021-40153 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 2.50% probability of exploitation in the next 30 days.

How do I fix CVE-2021-40153?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-40153?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST