CVE-2026-59197: Python Pillow

High severity, CVSS 8.2. EPSS: 0.4% chance of exploitation in the next 30 days.

Pillow is a Python imaging library. Prior to 12.3.0, Pillow's public rank-filter API can trigger a native heap out-of-bounds write when given a very large odd filter size because ImageFilter.RankFilter.filter() calls image.expand(size // 2, size // 2) before rank-filter size validation and ImagingExpand() computes output dimensions with unchecked signed int arithmetic. This issue is fixed in version 12.3.0.

Affected products

• Python Pillow: before 12.3.0 (fixed in 12.3.0)

Published 2026-07-14. Last modified 2026-07-21.