CVE-2026-84309

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.

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Weakness Type (CWE)

CWE-835 CWE-835

References

Other References

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

Frequently Asked Questions

What is CVE-2026-84309? +

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.

How do I check if I'm vulnerable to CVE-2026-84309? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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