CVE-2021-40153

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. High risk of data tampering, service disruption.

Exploit odds

2.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-08-27 15:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 04:06 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 2.5% in the next 30 days (EPSS).
• Severity: 8.1 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-08-27 15:15 UTC

Last modified

2026-06-17 04:06 UTC

Exploit probability

2.5% · EPSS, next 30 days

Weakness

CWE-22 · Path traversal

Record status

Modified

Affected

• squashfs-tools Project squashfs-tools 4.5
• Fedoraproject Fedora 34
• Debian Linux 9.0
• Debian Linux 10.0
• Redhat Enterprise Linux 7.0
• Redhat Enterprise Linux 8.0
• Fedoraproject Fedora 33

Attack profile CVSS 3.1 · 8.1

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-40153.md and follow it. Check whether this project is affected by CVE-2021-40153. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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