Heap-based buffer overflow in Pillow - CVE-2026-42309
Published: April 23, 2026
Vulnerability identifier: #VU127174
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-42309
CWE-ID: CWE-122
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a heap-based buffer overflow in coordinate-processing APIs such as ImagePath.Path, ImageDraw.ImageDraw.polygon, and ImageDraw.ImageDraw.line when processing nested list coordinates. A remote attacker can pass nested lists as coordinates to cause a denial of service.
The issue was introduced in Pillow 11.2.1.
Affected software
Pillow
How to mitigate CVE-2026-42309
Install security update from vendor's website.
Pillow - update to 12.2.0