Inefficient Algorithmic Complexity in PyPDF - CVE-2026-33123
Published: April 10, 2026
Vulnerability identifier: #VU125810
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-33123
CWE-ID: CWE-407
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to inefficient algorithmic complexity in array-based stream decoding when processing a crafted PDF containing an array-based stream with many entries. A remote attacker can supply a specially crafted PDF to cause a denial of service.
Exploitation requires the application to access an array-based stream with many entries in the PDF.
Affected software
PyPDF
How to mitigate CVE-2026-33123
Install security update from vendor's website.
PyPDF - update to 6.9.1