Inefficient regular expression complexity in PyPDF - CVE-2026-22691
Published: January 12, 2026
Vulnerability identifier: #VU121161
CSH Severity: Medium
CVSS v4: 6.7 [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]
CVE-ID: CVE-2026-22691
CWE-ID: CWE-1333
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
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.
Affected software
PyPDF
Fusion Content-Aware Storage
IBM Fusion HCI
IBM Watson Discovery for IBM Cloud Pak for Data
Fusion Content-Aware Storage
IBM Fusion HCI
IBM Watson Discovery for IBM Cloud Pak for Data
How to mitigate CVE-2026-22691
Install updates from vendor's website.
PyPDF - update to 6.6.0
Fusion Content-Aware Storage - update to 1.1.1
IBM Fusion HCI - update to 2.13.0
IBM Watson Discovery for IBM Cloud Pak for Data - update to 5.3.2
Fusion Content-Aware Storage - update to 1.1.1
IBM Fusion HCI - update to 2.13.0
IBM Watson Discovery for IBM Cloud Pak for Data - update to 5.3.2