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.
Weakness
The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Pillow | Python | 8.1.0 (including) | 13.0.0 (excluding) |
Potential Mitigations
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
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-5xm2-6676-qcp9