Infinite Loop in PyPDF Due to Malicious PDF Merge

Compliance Impact

The provided information does not specify any direct impact of CVE-2026-54531 on compliance with common standards and regulations such as GDPR or HIPAA.

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Executive Summary

This vulnerability exists in the pypdf library, a pure-python PDF library. Before version 6.13.0, an attacker could craft a specially designed PDF file that, when merged with a file containing outlines into a writer, causes the library to enter an infinite loop.

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Impact Analysis

The impact of this vulnerability is that it can cause the pypdf library to hang indefinitely due to an infinite loop when processing maliciously crafted PDF files. This can lead to denial of service conditions in applications that rely on pypdf for PDF processing.

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Mitigation Strategies

To mitigate this vulnerability, you should upgrade the pypdf library to version 6.13.0 or later, where the issue has been fixed.

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Detection Guidance

This vulnerability involves an infinite loop triggered by processing crafted PDF files with outlines during merging in the pypdf library versions prior to 6.13.0.

Detection would involve identifying attempts to process or merge PDF files containing outlines using vulnerable versions of pypdf.

Since the vulnerability manifests as an infinite loop during PDF processing, monitoring for unusually long or hanging pypdf processes when handling PDFs with outlines could be an indicator.

There are no specific commands or network detection signatures provided in the available resources.

A practical approach is to verify the version of pypdf installed on your system and upgrade to version 6.13.0 or later to mitigate the issue.

To check the installed pypdf version, you can run the following command in your Python environment:

• python -c "import pypdf; print(pypdf.__version__)"

If you observe processes hanging or looping indefinitely during PDF merging operations, especially with files containing outlines, this may indicate exploitation attempts.

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