CVE-2026-33123

pypdf has inefficient decoding of array-based streams

State: Published
Severity: 5.1 Medium
Published: Mar 20, 2026
Updated: Mar 20, 2026
Reserved: Mar 17, 2026

Description

pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage. Exploitation requires accessing an array-based stream with many entries. This issue has been fixed in version 6.9.1.

Scores

CVSS	Score	Vector	Source
4.0	5.1 Medium	CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N	GitHub_M

Weaknesses

CWE-400 Uncontrolled Resource Consumption
CWE-407 Inefficient Algorithmic Complexity

Affected Products

Product	Versions
pypdfpy-pdf	< 6.9.1Affected

References

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