CVE-2026-96637 · GHSA-g842-9rc4-69pw
Pillow: Decompression bomb check bypass in SpiderImagePlugin.seek() leads to unbounded allocation DoS
- Risk score
- 58/100
- CVSS
- 7.1 v4.0
- Exploit chance (30 days)
- 0.3%
- Published
- 21 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- 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…
- Affected
- pillow (pip) < 13.0.0
- Fix
- Upgrade pillow to 13.0.0 or later.
- Exploitation
- No known exploitation
Why it is Yellow
- CVSS 7.1 high
- Remotely exploitable without logging in
- On your watchlist: PyPI
Affected packages
| Package | Ecosystem | Vulnerable | Fixed in |
|---|---|---|---|
| pillow | pip | < 13.0.0 | 13.0.0 |
References
- 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
- https://github.com/advisories/GHSA-g842-9rc4-69pw
Original 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.
Last activity 21 Oct 2026. Patch Forecast updates every hour.