high7.1
CVE-2026-96637
Pillow: Decompression bomb check bypass in SpiderImagePlugin.seek() leads to unbounded allocation DoS
Impact
Pillow is a Python imaging library. Prior to 13.0.0, SpiderImageFile.seek() in src/PIL/SpiderImagePlugin.py reparses a later SPIDER stack frame and replaces self._size without rerunning Image._decompression_bomb_check(). A tiny file can use a safe first frame to pass Image.open() and then declare very large dimensions in a later mode F frame. Loading that frame allocates approximately four bytes per attacker-declared pixel and can consume multiple gigabytes of memory. This issue is fixed in version 13.0.0.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | pillow | < 13.0.0 | 13.0.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Python | Pillow | before 13.0.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-g842-9rc4-69pw
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-g842-9rc4-69pw
- https://nvd.nist.gov/vuln/detail/CVE-2026-96637
- https://github.com/python-pillow/Pillow/pull/10076
- https://github.com/python-pillow/Pillow/commit/7cb0e02389d8aac2a60896a490f572db0b07b841
- https://github.com/python-pillow/Pillow/releases/tag/13.0.0