pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions prior to 6.10.1 can craft a PDF which leads to long runtimes. This requires cross-reference streams with wrong large `/Size` values or object streams with wrong large `/N` values. This has been fixed in pypdf 6.10.1. As a workaround, one may apply the changes from the patch manually.
CVE-2026-41168
CVSS base score
5.3 (v3.1)
Severity
MEDIUM
Attack vector
Network
Weakness
CWE-834
Last modified
November 2, 2026
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Affected products
py-pdf pypdf
References
- github.com Patch
- github.com Issue Tracking, Patch
- github.com Product, Release Notes
- github.com Mitigation, Patch, Vendor Advisory