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

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.

CVSS vector

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

Attack vector

Network

Complexity

Low

Privileges

None

User interaction

Required

Confidentiality

High

Integrity

None

Availability

High

Scope

Unchanged

Exploitation

Is it being used?

Exploit prediction (EPSS)0.4% · higher than 35% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

PI

Pillow · python-pillow

< 13.0.0 · source: vendor, NVD