CVE-2026-112399: Pillow: APNG background disposal allocates full canvas before decompression bomb check

Description

Pillow is a Python imaging library. From 8.1.0 until 13.0.0, Pillow can allocate an APNG disposal background at the full canvas size before applying the decompression-bomb check. A crafted APNG with a small first frame, a very large declared canvas, and background disposal or first-frame OP_PREVIOUS reaches PngImageFile._seek while Image.open() positions frame zero. The full-canvas allocation occurs inside Image.open() without requiring pixel loading or frame iteration. This can exhaust memory and deny service. This issue is fixed in version 13.0.0.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack vector

Network

Complexity

Low

Privileges

None

User interaction

None

Confidentiality

None

Integrity

None

Availability

High

Scope

Unchanged

Exploitation

Is it being used?

Exploit prediction (EPSS)0.4% · higher than 32% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

PI

Pillow · python-pillow

>= 8.1.0, < 13.0.0 · source: vendor, NVD