CVE-2026-54651CWE-835

pypdf: Possible infinite loop when processing threads/articles in writer

Medium · published June 22, 2026

CVSS v4.0
6.9
EPSS
0%
Percentile
4.6
In the wild
Unconfirmed
What it is

pypdf is a free and open-source pure-python PDF library. Prior to 6.13.1, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires merging a file with threads/articles into a writer. This vulnerability is fixed in 6.13.1.

The record
Technical detail
CVSS v4.0
6.9 · MEDIUM
Vector
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
EPSS
0.00158 · 4.6th percentile
Weakness
CWE-835 · Loop with Unreachable Exit Condition ('Infinite Loop')
Published
2026-06-22T20:28Z
EPSS history
Timeline
  • 22 JUN 20:28Z
    pypdf: Possible infinite loop when processing threads/articles in writer
    cvelistv5