What’s Vulnerable › Vulnerabilities

CVE-2026-59200: Pillow: Decompression Bomb DoS via PdfParser.PdfStream.decode()

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-07-14 · updated 2026-10-24
• Weakness: CWE-400

Description

Pillow is a Python imaging library. From 5.1.0 until 12.3.0, PdfParser.PdfStream.decode() in PIL/PdfParser.py calls zlib.decompress() with bufsize set to the PDF stream Length field without bounding the decompressed output size, allowing a crafted FlateDecode PDF stream to exhaust memory from a small file. This issue is fixed in version 12.3.0.

Affected products

• python-pillow Pillow: from 5.1.0 before 12.3.0 — fixed in 12.3.0
• Pypi Pillow: from 5.1.0 before 12.3.0; 10.0.0, 10.0.1, 10.1.0, 10.2.0, 10.3.0, 10.4.0 (+42) — fixed in 12.3.0

How to fix

Upgrade to a fixed version: python-pillow Pillow 12.3.0; Pypi Pillow 12.3.0. Check the vendor advisory for mitigations.

References

• https://github.com/python-pillow/Pillow/commit/f7a31ea75e460e108c37126da1f47812f21f6b09
• https://github.com/python-pillow/Pillow/pull/9718
• https://github.com/python-pillow/Pillow/releases/tag/12.3.0
• https://github.com/python-pillow/Pillow/security/advisories/GHSA-jjj6-mw9f-p565
• https://github.com/python-pillow/Pillow/security/advisories/GHSA-jjj6-mw9f-p565

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