Heap-based buffer overflow in Pillow - CVE-2026-59205
Published: July 7, 2026
Vulnerability identifier: #VU137002
CSH Severity: Medium
CVSS v4.0: 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/E:U/U:Green
CVE-ID: CVE-2026-59205
CWE-ID: CWE-122
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Alex Clark and Contributors
Affected software:
Pillow
Pillow
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a heap-based buffer overflow in ImageCmsTransform.apply() when processing a caller-supplied output image whose mode does not match the transform's declared output mode. A remote attacker can supply a crafted output image object to cause a denial of service.
The issue is reachable through Pillow's public ImageCms API, and the source image pixels can influence the bytes written out of bounds.
How to mitigate CVE-2026-59205
Install security update from vendor's website.