CVE-2026-59197: python-pillow pillow Integer Overflow or Wraparound

Vulnerability summary

CVE-2026-59197 is a high (CVSS 8.2) Integer Overflow or Wraparound vulnerability in python-pillow pillow. EPSS estimates a 0.45% chance of exploitation in the next 30 days, higher than 37.3% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 14-07-2026
   PublishedVulnerability first disclosed.
2. 21-07-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-190Integer Overflow or WraparoundThe product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.