Medium 6.9Published Sep 1, 2026

CVE-2026-84309pypdf: Possible infinite loop for TreeObject.insert_child

Updated under an hour ago (2026-10-19 07:10 UTC)

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It affects py-pdf pypdf and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for py-pdf pypdf

Exploited in the last 30 days

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: 6.9 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-835
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Sep 2, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

py-pdf pypdf py_pdf:pypdf (from the name)	before 6.16.0	CNA record
pypdf_project pypdf pypdf_project:pypdf	before 6.16.0	NVD

References

https://github.com/py-pdf/pypdf/security/advisories/GHSA-jp53-mhqp-8xcgx-refsource-confirm, patch, vendor-advisory
https://github.com/py-pdf/pypdf/pull/3964x-refsource-misc, patch
https://github.com/py-pdf/pypdf/commit/c9ba557d565d57c53a0b3a0be06c0a4c29b0559bx-refsource-misc, patch
https://github.com/py-pdf/pypdf/releases/tag/6.16.0x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.