Buffer overflow in Python Pillow
CVE-2026-59197
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.
Vulnerability class: Integer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H.
EPSS exploit prediction
EPSS: 0.004 (37.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 37.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Python Pillow
- Python-Pillow Pillow — versions < 12.3.0
Weakness classification (CWE)
References
- github.com/python-pillow/Pillow/security/advisories/GHSA-xj96-63gp-2gmr (Exploit, Vendor Advisory)
- github.com/python-pillow/Pillow/pull/9695 (Patch, Issue Tracking)
- github.com/python-pillow/Pillow/commit/cce3bdb867c77a3420261ed1bfdb6b0787ec8fc1 (Patch)
- github.com/python-pillow/Pillow/releases/tag/12.3.0 (Release Notes)
Frequently asked questions
- What is CVE-2026-59197?
- CVE-2026-59197 is a high-severity vulnerability in Python Pillow, classified under Integer Overflow or Wraparound. CVSS score: 8.2/10. Published 2026-07-14.
- How severe is CVE-2026-59197?
- High severity. CVSS v3 base score is 8.2 out of 10.