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.
https://github.com/python-pillow/Pillow/security/advisories/GHSA-9v9v-9qvf-h2hj
https://github.com/python-pillow/Pillow/releases/tag/13.0.0
https://github.com/python-pillow/Pillow/pull/10120
https://github.com/python-pillow/Pillow/commit/4cf46bee338304c5c8968fd7f132ba0d40c428b7
Published: 2026-10-21
Updated: 2026-10-21
Base Score: 5.8
Vector: CVSS2#AV:N/AC:M/Au:N/C:P/I:N/A:P
Severity: Medium
Base Score: 5.5
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Severity: Medium
Base Score: 7.1
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
Severity: High