Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Pillow versions 10.3.0 up to but not including 12.2.0 are affected. When decoding a GZIP-compressed FITS image, Pillow did not limit how much data it read, so a specially crafted FITS file could consume unbounded memory and cause a denial of service through an out-of-memory crash or severe slowdown. Upgrade to Pillow 12.2.0. Alternatively, open only image formats other than FITS by passing an explicit formats list to Image.open.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 8.7 | High | 4.0 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0067, the 52nd percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:11 UTC First seen by agentprime
- 31 Oct 2026, 14:11 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-whj4-6x5x-4v2j
- OSV: GHSA-whj4-6x5x-4v2j
- github.com/python-pillow/Pillow/security/advisories/GHSA-whj4-6x5x-4v2j
- nvd.nist.gov/vuln/detail/CVE-2026-40192
- github.com/python-pillow/Pillow/pull/9521
- github.com/python-pillow/Pillow/commit/3cb854e8b2bab43f40e342e665f9340d861aa628
- github.com/python-pillow/Pillow
- pillow.readthedocs.io/en/stable/releasenotes/12.2.0.html#prevent-fits-decompression-bomb