CVE-2026-59197

Name of the Vulnerable Software and Affected Versions Pillow versions prior to 12.3.0

Description The public rank-filter API in the Pillow Python imaging library allows a native heap out-of-bounds write when a very large odd filter size is provided. This occurs because the ImageFilter.RankFilter.filter() function calls image.expand(size // 2, size // 2) before validating the rank-filter size, and the ImagingExpand() function calculates output dimensions using unchecked signed int arithmetic, which is a type of calculation that does not account for values exceeding the maximum limit of a signed integer.

Recommendations Update to version 12.3.0.