Resource exhaustion in Py-Pdf Pypdf

CVE-2026-119209

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.3, pypdf can consume excessive memory while opening a crafted PDF containing cross-reference streams that declare very large entry counts. Highly compressible streams and /Prev chains can multiply the number of parsed entries across a document, while negative /Index counts can bypass the existing per-stream clamp. This issue is fixed in version 6.21.3.

Vulnerability class: DoS (Denial of Service)

Published .

EPSS exploit prediction

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Affected products

Weakness classification (CWE)

References