CVE-2026-96642: pillow — Fix

Description

Pillow is a Python imaging library. Prior to 13.0.0, the TarIO initializer in src/PIL/TarIO.py accepts a negative octal member size and computes a backward seek that returns to the same 512-byte header. When the requested member name does not match, the parser repeatedly reads that header, consumes a full CPU core, and never returns. TarIO is reached only when an application directly uses PIL.TarIO.TarIO rather than the default Image.open() path. This issue is fixed in version 13.0.0.

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CVSS v3.1 Score

6.5

MEDIUM

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

EPSS — Exploit Prediction

0.0035

Probability of exploitation

0.28%

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-835 CWE-835

Affected Products

Vendor	Product	Versions
python	pillow	< 13.0.0

References

Advisories & Patches

https://github.com/python-pillow/Pillow/commit/19b695fdcc5eddc37374e2b1645fc4185edaf71d https://github.com/python-pillow/Pillow/security/advisories/GHSA-3j72-p6qg-6xp7

Other References

https://github.com/python-pillow/Pillow/pull/10012 https://github.com/python-pillow/Pillow/releases/tag/13.0.0

Frequently Asked Questions

What is CVE-2026-96642? +

Pillow is a Python imaging library. Prior to 13.0.0, the TarIO initializer in src/PIL/TarIO.py accepts a negative octal member size and computes a backward seek that returns to the same 512-byte header. When the requested member name does not match, the parser repeatedly reads that header, consumes a full CPU core, and never returns. TarIO is reached only when an application directly uses PIL.TarIO.TarIO rather than the default Image.open() path. This issue is fixed in version 13.0.0. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-96642? +

CVE-2026-96642 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0035, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-96642? +

CVE-2026-96642 affects products from python, specifically: pillow. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-96642? +

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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