CVE-2026-22691CWE-1333CWE-400

pypdf has possible long runtimes for malformed startxref

Low · published January 10, 2026

CVSS v4.0
2.7
EPSS
0%
Percentile
36.6
In the wild
Unconfirmed
What it is

pypdf is a free and open-source pure-python PDF library. Prior to version 6.6.0, pypdf has possible long runtimes for malformed startxref. An attacker who uses this vulnerability can craft a PDF which leads to possibly long runtimes for invalid startxref entries. When rebuilding the cross-reference table, PDF files with lots of whitespace characters become problematic. Only the non-strict reading mode is affected. Only the non-strict reading mode is affected. This issue has been patched in version 6.6.0.

The record
Technical detail
CVSS v4.0
2.7 · LOW
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
EPSS
0.00433 · 36.6th percentile
Weaknesses
CWE-1333 · Inefficient Regular Expression Complexity; CWE-400 · Uncontrolled Resource Consumption
Published
2026-01-10T04:46Z
EPSS history
Timeline
  • 10 JAN 04:46Z
    pypdf has possible long runtimes for malformed startxref
    cvelistv5