CVE-2026-84309
Medium
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.
SeverityMedium
CVSS5.5
Exploit probability—
ProductPypdf
PublishedSep 1, 2026
First seenSep 1, 2026
Weakness typeCWE-835CWE-835
How to fix
Update
- pypdf_project pypdf6.16.0 or later
- pypdf6.16.0 or later
- py-pdf pypdf6.16.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| pypdf_project pypdf | v < 6.16.0 | 6.16.0 |
| pypdfPyPI | v < 6.16.0 | 6.16.0 |
| py-pdf pypdf | v < 6.16.0 | 6.16.0 |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
In the Intelligence 360 plan
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.