CVE-2026-112399

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.

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Weakness Type (CWE)

CWE-789 CWE-789

References

Other References

https://github.com/python-pillow/Pillow/commit/f1acfc54c53502948d0d14121872061df931db48 https://github.com/python-pillow/Pillow/releases/tag/13.0.0 https://github.com/python-pillow/Pillow/security/advisories/GHSA-5xm2-6676-qcp9

Frequently Asked Questions

What is CVE-2026-112399? +

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.

How do I check if I'm vulnerable to CVE-2026-112399? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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