Excessive Iteration in PyPDF - #VU156726
Published: October 21, 2026
Vulnerability identifier: #VU156726
CSH Severity: Low
CVSS v4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-834
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service through prolonged PDF processing.
The vulnerability exists due to excessive iteration in the pypdf cross-reference (xref) table parser when processing a PDF with large or incorrect upper limits in its xref table. A remote attacker can trick a user into opening a crafted PDF to cause excessively long processing times.
Affected software
PyPDF
Remediation
Install security update from vendor's website.
PyPDF - update to 6.21.2