CVE-2026-59203: pillow — Exploit & Fix

Description

Pillow is a Python imaging library. From 12.0.0 through 12.2.0, Pillow's EPS parser in PIL/EpsImagePlugin.py accepts a negative byte count in the %%BeginBinary directive, allowing a crafted EPS file to cause Image.open() to seek backwards to the same directive and parse it repeatedly in an infinite loop. This issue is fixed in version 12.3.0.

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CVSS v3.1 Score

5.3

MEDIUM

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

EPSS — Exploit Prediction

0.0039

Probability of exploitation

0.31%

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	12.0.0 — 12.3.0

References

Advisories & Patches

https://github.com/python-pillow/Pillow/commit/03992618118b4a76b6163cd72ab5ecd684133b83 https://github.com/python-pillow/Pillow/pull/9708 https://github.com/python-pillow/Pillow/security/advisories/GHSA-pg7v-jwj7-p798 https://github.com/python-pillow/Pillow/security/advisories/GHSA-pg7v-jwj7-p798

Exploits

https://github.com/python-pillow/Pillow/security/advisories/GHSA-pg7v-jwj7-p798 https://github.com/python-pillow/Pillow/security/advisories/GHSA-pg7v-jwj7-p798

Other References

https://github.com/python-pillow/Pillow/releases/tag/12.3.0

Frequently Asked Questions

What is CVE-2026-59203? +

Pillow is a Python imaging library. From 12.0.0 through 12.2.0, Pillow's EPS parser in PIL/EpsImagePlugin.py accepts a negative byte count in the %%BeginBinary directive, allowing a crafted EPS file to cause Image.open() to seek backwards to the same directive and parse it repeatedly in an infinite loop. This issue is fixed in version 12.3.0. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-59203? +

CVE-2026-59203 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0039, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-59203? +

CVE-2026-59203 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-2026-59203? +

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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