Description
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.
Affected products
py-pdf: pypdf
References4
- github.com/py-pdf/pypdf/security/advisories/GHSA-4pxv-j86v-mhcw PatchVendor Advisory
- github.com/py-pdf/pypdf/commit/c50a0104cf083356f7c7f5d61410466a… Patch
- github.com/py-pdf/pypdf/pull/3735 Issue TrackingPatch
- github.com/py-pdf/pypdf/releases/tag/6.10.2 Release Notes
Metrics
- CVSS 3.1
-
6.5
MEDIUM
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - CVSS 4.0
-
4.8
MEDIUM
Score source: CNA
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 12 · as of 13 November 2026
- CWE
- CWE-834
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.