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.

Scores

Weaknesses (CWE)

• CWE-125

Advisories

• GHSA-9v9v-9qvf-h2hj — Pillow: Heap over-read in WMF/EMF rendering via 16-bit dimension truncation (Windows builds)
• PYSEC-2026-4343 — 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 ha

European references

• ENISA EUVD · EUVD-2026-107563
• GCVE · GCVE-0-2026-96644

Affected configurations (NVD CPE)

• cpe:2.3:a:python:pillow:*:*:*:*:*:*:*:* < 13.0.0

Affected products

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

Sources