Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.21.0, an attacker can craft a PDF containing arrays or dictionaries with many elements, causing parsing to consume large amounts of memory. This issue is fixed in version 6.21.0.
Affected products
py-pdf: pypdf
References4
- github.com/py-pdf/pypdf/security/advisories/GHSA-f54x-cmq8-qg57 Vendor AdvisoryPatch
- github.com/py-pdf/pypdf/commit/18bd2981a74479483a0b9507602c58a6… Patch
- github.com/py-pdf/pypdf/pull/4218 Issue TrackingPatch
- github.com/py-pdf/pypdf/releases/tag/6.21.0 Release Notes
Metrics
- CVSS 3.1
-
3.3
LOW
Score source: NVD
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L - CVSS 4.0
-
6.0
MEDIUM
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/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: 23 · as of 8 November 2026
- CWE
- CWE-400CWE-770
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.