Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Pillow versions before 12.3.0 are vulnerable: the GdImageFile plugin reads image dimensions from a GD file header without running the decompression bomb check, so the check is bypassed when a caller uses the plugin's own open function. An attacker who can supply a crafted GD file to an application that calls that function and then loads the image can force a very large memory allocation, which can crash the process. Upgrade to Pillow 12.3.0 or later.
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 |
|---|---|---|---|---|
| 7.5 | High | 3.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0052, the 44th percentile, on 15 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 3 Jul 2026, 08:35 UTC Published by the maintainers as a GitHub repository advisory
- 31 Oct 2026, 14:11 UTC First seen by agentprime
- 31 Oct 2026, 14:11 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-phj9-mv4w-65pm
- OSV: GHSA-phj9-mv4w-65pm
- github.com/python-pillow/Pillow/security/advisories/GHSA-phj9-mv4w-65pm
- nvd.nist.gov/vuln/detail/CVE-2026-55380
- github.com/python-pillow/Pillow/commit/f39b0ae6624eb2d7c5c5d651d9bb5fdbd96a8675
- github.com/pypa/advisory-database/tree/main/vulns/pillow/PYSEC-2026-2256.yaml
- github.com/python-pillow/Pillow
- github.com/python-pillow/Pillow/blob/main/docs/releasenotes/12.3.0.rst