Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.21.2, an incomplete remediation for repeated malformed cross-reference entries in GHSA-55h5-xmcq-c37v could still trigger a complete PDF stream reload during each recovery attempt even when a recovery cache was present, causing crafted cross-reference streams to produce long runtimes. This issue is fixed in version 6.21.2.
References4
Metrics
- CVSS 4.0
-
7.1
HIGH
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:N/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: 36 · as of 8 November 2026
- CWE
- CWE-400CWE-407
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.