Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Pillow versions 5.1.0 up to but not including 12.3.0 are affected by a denial-of-service flaw in PdfParser.PdfStream.decode(), which decompresses PDF streams without an upper bound on output size. An attacker who can submit a crafted PDF of about 950 KB to an application that uses PdfParser to read it can exhaust server memory, causing crashes or severe slowdown for all users. Upgrade to Pillow 12.3.0 or later. The source gives no workaround besides avoiding PdfParser on untrusted files.
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 0.0039, the 33rd percentile, on 15 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 7 Jul 2026, 08:58 UTC Published by the maintainers as a GitHub repository advisory
- 31 Oct 2026, 14:35 UTC First seen by agentprime
- 31 Oct 2026, 14:35 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-jjj6-mw9f-p565
- OSV: GHSA-jjj6-mw9f-p565
- github.com/python-pillow/Pillow/security/advisories/GHSA-jjj6-mw9f-p565
- nvd.nist.gov/vuln/detail/CVE-2026-59200
- github.com/python-pillow/Pillow/pull/9718
- github.com/python-pillow/Pillow/commit/f7a31ea75e460e108c37126da1f47812f21f6b09
- github.com/python-pillow/Pillow
- github.com/python-pillow/Pillow/releases/tag/12.3.0