Vulnerability Description
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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Python | Pillow | < 13.0.0 |
Related Weaknesses (CWE)
References
- https://github.com/python-pillow/Pillow/commit/7cb0e02389d8aac2a60896a490f572db0Patch
- https://github.com/python-pillow/Pillow/pull/10076Issue Tracking
- https://github.com/python-pillow/Pillow/releases/tag/13.0.0Release Notes
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-g842-9rc4-69pwVendor Advisory
FAQ
What is CVE-2026-96637?
CVE-2026-96637 is a vulnerability with a CVSS score of 6.5 (MEDIUM). 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._decompr...
How severe is CVE-2026-96637?
CVE-2026-96637 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-96637?
Check the references section above for vendor advisories and patch information. Affected products include: Python Pillow.