pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions prior to 6.10.2 can craft a PDF which leads to long runtimes. This requires loading a PDF with a large trailer `/Size` value in incremental mode. This has been fixed in pypdf 6.10.2. As a workaround, one may apply the changes from the patch manually.
https://github.com/py-pdf/pypdf/security/advisories/GHSA-4pxv-j86v-mhcw
https://github.com/py-pdf/pypdf/releases/tag/6.10.2
https://github.com/py-pdf/pypdf/pull/3735
https://github.com/py-pdf/pypdf/commit/c50a0104cf083356f7c7f5d61410466a57f5c88a
Published: 2026-04-22
Updated: 2026-04-22
Base Score: 5.8
Vector: CVSS2#AV:N/AC:M/Au:N/C:N/I:P/A:P
Severity: Medium
Base Score: 6.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Severity: Medium
Base Score: 4.8
Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Severity: Medium