Vulnerability · Published Oct 19, 2026 · Assigned by GitHub_M
CVE-2026-112399Pillow: APNG background disposal allocates full canvas before decompression bomb check
High 8.7
In plain English
A high-severity security flaw in Pillow from python-pillow. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | pillow | no fix listed | DEBIAN-CVE-2026-112399 |
| Debian:13 | pillow | no fix listed | DEBIAN-CVE-2026-112399 |
| Debian:14 | pillow | no fix listed | DEBIAN-CVE-2026-112399 |
| PyPI | pillow | 13.0.0 | GHSA-5xm2-6676-qcp9 |
| Ubuntu:22.04:LTS | pillow | no fix listed | UBUNTU-CVE-2026-112399 |
| Ubuntu:24.04:LTS | pillow | no fix listed | UBUNTU-CVE-2026-112399 |
| Ubuntu:26.04:LTS | pillow | no fix listed | UBUNTU-CVE-2026-112399 |
| Ubuntu:26.10 | pillow | no fix listed | UBUNTU-CVE-2026-112399 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| python-pillow | Pillow | >= 8.1.0, < 13.0.0 |
Weakness: CWE-789 · Vector: 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