CVE-2026-27025

Received Received - Intake

Denial of Service via Resource Exhaustion in pypdf /ToUnicode Parsing

Publication date: 2026-02-20

Last updated on: 2026-02-24

Assigner: GitHub, Inc.

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.1, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes and large memory consumption. This requires parsing the /ToUnicode entry of a font with unusually large values, for example during text extraction. This vulnerability is fixed in 6.7.1.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-02-20

Last Modified

2026-02-24

Generated

2026-07-06

AI Q&A

2026-02-21

EPSS Evaluated

2026-07-05

NVD

CVE-2026-27025

Affected Vendors & Products

Vendor	Product	Version / Range
pypdf_project	pypdf	to 6.7.1 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-834	The product performs an iteration or loop without sufficiently limiting the number of times that the loop is executed.

Attack-Flow Graph

Impact Analysis

The impact of this vulnerability is that processing a maliciously crafted PDF can lead to long runtimes and large memory consumption. This can degrade system performance, potentially causing denial of service conditions or resource exhaustion on systems that use the vulnerable pypdf versions.

Compliance Impact

I don't know

Detection Guidance

I don't know

Mitigation Strategies

To mitigate this vulnerability, you should upgrade the pypdf library to version 6.7.1 or later, where the issue has been fixed.

Executive Summary

This vulnerability exists in the pypdf library, a pure-python PDF library. Before version 6.7.1, an attacker could craft a specially designed PDF file that exploits the parsing of the /ToUnicode entry of a font with unusually large values. When such a PDF is processed, it can cause the library to consume excessive memory and run for a very long time.

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