Vulnerability · Published Oct 21, 2026 · Assigned by GitHub_M

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

High 7.1

In plain English

A high-severity out-of-bounds read in Pillow from python-pillow. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)7.1High

Exploit odds (30 days)0.4%top 67.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
PyPI	pillow	13.0.0	GHSA-9v9v-9qvf-h2hj
PyPI	pillow	13.0.0	PYSEC-2026-4343

Affected products (as reported)

Vendor	Product	Versions
python-pillow	Pillow	< 13.0.0

Weakness: CWE-125 · 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

References

https://github.com/python-pillow/Pillow/security/advisories/GHSA-9v9v-9qvf-h2hj x_refsource_CONFIRM
https://github.com/python-pillow/Pillow/pull/10120 x_refsource_MISC
https://github.com/python-pillow/Pillow/commit/4cf46bee338304c5c8968fd7f132ba0d40c428b7 x_refsource_MISC
https://github.com/python-pillow/Pillow/releases/tag/13.0.0 x_refsource_MISC