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Vulnerability record · CVE-2026-84309 · published 1 September 2026

CVE-2026-84309: Pypdf project pypdf vulnerability

PPypdf Project · Pypdf

pypdf is a free and open-source pure-python PDF library. Prior to 6.16.0, an attacker can craft a PDF whose cyclic tree structure causes pypdf/generic/_data_structures.py TreeObject.insert_child to follow /Next links indefinitely when a writing code path inserts a child, producing an infinite loop. This issue is fixed in version 6.16.0.

6.9 CVSS 4.0 Medium EPSS 0.19% · top 92.4% CWE-835 · CWE-835
6.9CVSS 4.0 base score
0.19%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
5 Oct 2026Last modified by NVD

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.16.0, an attacker can craft a PDF whose cyclic tree structure causes pypdf/generic/_data_structures.py TreeObject.insert_child to follow /Next links indefinitely when a writing code path inserts a child, producing an infinite loop. This issue is fixed in version 6.16.0.

CVSS:4.0/AV:L/AC:L/AT:N/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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/py-pdf/pypdf/commit/c9ba557d565d57c53a0b3a0be06c0a4c29b0559b Patch
https://github.com/py-pdf/pypdf/pull/3964 Patch
https://github.com/py-pdf/pypdf/releases/tag/6.16.0 Release Notes
https://github.com/py-pdf/pypdf/security/advisories/GHSA-jp53-mhqp-8xcg PatchVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-84309), CISA KEV, FIRST EPSS (scores of 2026-10-07). This page is refreshed as NVD updates the record.