Inefficient regular expression complexity in PyPDF - CVE-2026-22691
Published: January 12, 2026
Vulnerability identifier: #VU121161
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-22691
CWE-ID: CWE-1333
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Pypdf Project
Affected software:
PyPDF
PyPDF
Detailed vulnerability description
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to insufficient input validation when processing startxref entries with a regular expressions. A remote attacker can pass specially crafted PDF file containing multiple whitespace characters and perform regular expression denial of service (ReDos) attack.
How to mitigate CVE-2026-22691
Install updates from vendor's website.