CVE-2026-33123 PUBLISHED

pypdf has inefficient decoding of array-based streams

Assigner: GitHub_M
Reserved: 17.03.2026 Published: 20.03.2026 Updated: 20.03.2026

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.

Metrics

CVSS 4.0

CVSS Vector: 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
CVSS Score: 5.1

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Local	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	Low	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	py-pdf
Product	pypdf
Versions	Version < 6.9.1 is affected

References

Problem Types

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