CVE-2026-96640
Pillow PDF append accepts malformed shared page-tree DAG causing resource exhaustion
A public proof of concept exists; no exploitation attested.
- Published2026-10-21
- Fixed in13.0.0
- WeaknessCWE-400 · CWE-407
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
Pillow is a Python imaging library. From 5.1.0 until 13.0.0, PdfParser.linearize_page_tree() in src/PIL/PdfParser.py treats a PDF /Pages graph as a tree without tracking duplicate indirect references. When Image.save(..., format="PDF", append=True) processes an attacker-controlled existing PDF whose /Kids arrays repeatedly reference the same child /Pages node, Pillow expands the shared subtree as distinct pages. A compact malformed PDF can therefore create exponentially many page references and consume disproportionate CPU before the append completes. This issue is fixed in version 13.0.0.
Timeline
dates in UTC- 2026-10-2121:20CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-28 09:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-96640?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-96640?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD · OSV| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 13.0 | ≥ 5.1.0, < 13.0.0 | 13.0.0 | NVD · OSV |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Vendor advisories
pillow: pillow: Denial of Service via duplicate page references in PDF files
exploit-intelligence/vulnerability-analysis-rhel9 as a component of Exploit Intelligence · lightspeed-core/lightspeed-stack-rhel9 as a component of Lightspeed Core · lightspeed-core/rag-tool-cpu-rhel9 as a component of Lightspeed Core · +83 more
Fix
- Update Python pillow to 13.0.0
- No fix available, says the vendor Red Hat Product Security CVE-2026-96640 · 79 productsAffected
- No fix planned, says the vendor Red Hat Product Security CVE-2026-96640 · 7 productsWill not fix
Advisories and patches
- github.comPatch
- github.comRelease Notes
- github.comVendor Advisory
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CVSS 4.0 vector
- CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- Published
- 2026-10-21
- Last Modified
- 2026-10-28
- NVD status
- Modified
Frequently asked questions
What is CVE-2026-96640?
Is CVE-2026-96640 actively exploited?
What is the CVSS score for CVE-2026-96640?
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Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.