CVE-2026-119209

pypdf: Possible large memory usage when parsing cross-reference streams

State: Published
Severity: 7.1 High
Published: Oct 29, 2026
Updated: Oct 29, 2026
Reserved: Oct 29, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
4.0	7.1 High	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	GitHub_M

Weaknesses

CWE-400 Uncontrolled Resource Consumption
CWE-770 Allocation of Resources Without Limits or Throttling

Affected Products

Product	Versions
pypdfpy-pdf	< 6.21.3Affected

References

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