Description
pypdf is a free and open-source pure-python PDF library. Prior to version 6.6.0, pypdf has possible long runtimes for missing /Root object with large /Size values. An attacker who uses this vulnerability can craft a PDF which leads to possibly long runtimes for actually invalid files. This can be achieved by omitting the /Root entry in the trailer, while using a rather large /Size value. Only the non-strict reading mode is affected. This issue has been patched in version 6.6.0.
Scores
CVSS v3
5.3
EPSS
0.0002
EPSS Percentile
5.4%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-400
Status
published
Products (2)
pypdf_project/pypdf
< 6.6.0
pypi/pypdf
0 - 6.6.0PyPI
Published
Jan 10, 2026
Tracked Since
Feb 18, 2026