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.
https://github.com/py-pdf/pypdf/security/advisories/GHSA-jj6c-8h6c-hppx
https://github.com/py-pdf/pypdf/releases/tag/6.10.1
https://github.com/py-pdf/pypdf/pull/3733
https://github.com/py-pdf/pypdf/commit/62338e9d36419cf193ccec7331784f45df1d70b3
Published: 2026-04-22
Updated: 2026-04-24
Base Score: 5
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P
Severity: Medium
Base Score: 5.3
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Severity: Medium
Base Score: 6.9
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
Severity: Medium
EPSS: 0.00042