CVE-2026-40931

Description

Compressing is a compressing and uncompressing lib for node. Prior to 2.1.1 and 1.10.5, the patch for CVE-2026-24884 relies on a purely logical string validation within the isPathWithinParent utility. This check verifies if a resolved path string starts with the destination directory string but fails to account for the actual filesystem state. By exploiting this "Logical vs. Physical" divergence, an attacker can bypass the security check using a Directory Poisoning technique (pre-existing symbolic links). This vulnerability is fixed in 2.1.1 and 1.10.5.

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CVSS v3.1 Score

8.4

HIGH

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

EPSS — Exploit Prediction

0.0002

Probability of exploitation

0.05%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-59 CWE-59

Affected Products

Vendor	Product	Versions
node-modules	compressing	< 1.10.5
node-modules	compressing	2.0.0 — 2.1.1

References

Advisories & Patches

https://github.com/node-modules/compressing/security/advisories/GHSA-4c3q-x735-j3r5 https://github.com/node-modules/compressing/security/advisories/GHSA-4c3q-x735-j3r5

Exploits

https://github.com/node-modules/compressing/security/advisories/GHSA-4c3q-x735-j3r5 https://github.com/node-modules/compressing/security/advisories/GHSA-4c3q-x735-j3r5

Frequently Asked Questions

What is CVE-2026-40931? +

Compressing is a compressing and uncompressing lib for node. Prior to 2.1.1 and 1.10.5, the patch for CVE-2026-24884 relies on a purely logical string validation within the isPathWithinParent utility. This check verifies if a resolved path string starts with the destination directory string but fails to account for the actual filesystem state. By exploiting this "Logical vs. Physical" divergence, an attacker can bypass the security check using a Directory Poisoning technique (pre-existing symbolic links). This vulnerability is fixed in 2.1.1 and 1.10.5. It has a CVSS v3.1 base score of 8.4 (HIGH).

How severe is CVE-2026-40931? +

CVE-2026-40931 has a CVSS v3.1 score of 8.4 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0002, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-40931? +

CVE-2026-40931 affects products from node-modules, specifically: compressing. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-40931? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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