What’s Vulnerable › Vulnerabilities

CVE-2026-54059: Pillow: PcfFontFile._load_bitmaps()`: `Image.frombytes()` called without `_decompression_bomb_check()` — bomb protection bypass via PCF font loading

• 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: 2026-07-06 · updated 2026-10-25
• Weakness: CWE-789

Description

Pillow is a Python imaging library. Prior to 12.3.0, PIL/PcfFontFile.py _load_bitmaps() read glyph dimensions from the PCF METRICS section and passed them directly to Image.frombytes() without calling Image._decompression_bomb_check(), allowing crafted PCF font data to cause excessive memory allocation. This issue is fixed in version 12.3.0.

Affected products

• python-pillow Pillow: before 12.3.0 — fixed in 12.3.0
• Pypi Pillow: before 12.3.0; 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 (+100) — 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/blob/main/docs/releasenotes/12.3.0.rst
• https://github.com/python-pillow/Pillow/commit/0a263e6264aa5399988d9acd3bbfbca2ca3ec77d
• https://github.com/python-pillow/Pillow/security/advisories/GHSA-8v84-f9pq-wr9x
• https://github.com/python-pillow/Pillow/security/advisories/GHSA-8v84-f9pq-wr9x

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