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 I

highCVSS 8.2CVE-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.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: high — CVSS 8.2
Published: 2026-07-14
Last updated: 2026-07-21
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-59197

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-591970.44% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 36% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-59197	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for Pillow is a

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

medium[NEW] [medium] Red Hat Enterprise Linux (python-pillow): Multiple vulnerabilities allow denial of servicecert-bund · 2026-07-31
high[NEW] [high] Red Hat Enterprise Linux (Pillow): Multiple vulnerabilitiescert-bund · 2026-07-31
high[NEW] [high] Red Hat Satellite (foreman, python-pillow, go): Multiple vulnerabilitiescert-bund · 2026-07-30
highGHSA-9hw9-ch79-4vh6: Pillow: Controlled heap out-of-bounds write in Pillow `ImageCmsTransform.apply()` via out…ghsa · 2026-07-20
highGHSA-vjc4-5qp5-m44j: Pillow JPEG2000 tiled decode retains a growing scratch buffer and can be used for denial …ghsa · 2026-07-20
mediumGHSA-pg7v-jwj7-p798: Pillow EpsImagePlugin negative %%BeginBinary byte count causes infinite loop denial of se…ghsa · 2026-07-20