Pillow: FontFile.compile(): Image.new() called without _decompression_bomb_check()

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-54060: 0.42% estimated exploitation activity in the next 30 days; percentile 36.18 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Description PIL/FontFile.py FontFile.compile() assembles per-glyph images into a single combined bitmap using Image.new("1", (xsize, ysize)) without calling Image.decompressionbombcheck(). This is the base-class method shared by both BdfFontFile and PcfFontFile, and it is triggered whenever a loaded font is converted to an ImageFont or saved. Neither BdfFontFile.BdfFontFile(fp) nor PcfFontFile.PcfFontFile(fp) is registered with Image.registeropen(), so Pillow's standard decompression bomb guard never fires for font objects. The compile step is the final opportunity to check the combined allocation — and it has no check. Vulnerable code (PIL/FontFile.py lines ~64–92): "Slow accumulation" attack — per-glyph dimensions stay BELOW warning threshold: | Metric | Per-glyph (800 × 875) | Combined bitmap (256 glyphs) | |---|---|---| | Pixel count | 700,000 | 179,200,000 | | DecompressionBombWarning threshold (89.4M) | 0.008× — no warning | 2.0× — above warning | | DecompressionBombError…

Published by the source

20 Jul 2026, 21:08 UTC

Last modified by the source

10 Sep 2026, 03:51 UTC

Source last checked

26 Oct 2026, 13:49 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-5x94-69rx-g8h2

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-5x94-69rx-g8h2

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# Patch Next advisory brief: CVE-2026-54060

Advisory: Pillow: `FontFile.compile()`: `Image.new()` called without `_decompression_bomb_check()`
IDs: CVE-2026-54060, GHSA-5x94-69rx-g8h2
Record: https://patchnext.com/advisories/cve-2026-54060 (revision 2, source checked 26 Oct 2026, 13:49 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pillow 12.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pillow: affected < 12.3.0; fixed in 12.3.0

## Suggested inspection (read-only)
- `python -m pip show pillow`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pillow.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-5x94-69rx-g8h2 (OSV record GHSA-5x94-69rx-g8h2 lists affected ranges: PyPI pillow >=0 <12.3.0 (fixed))
- Verified: https://github.com/advisories/GHSA-5x94-69rx-g8h2 (GitHub-reviewed advisory GHSA-5x94-69rx-g8h2 lists affected ranges: PyPI pillow >=0 <12.3.0)

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