Memory Exhaustion in PyPDF via Malicious PDF

Executive Summary

This vulnerability exists in the pypdf library, a pure-python PDF library. Before version 6.13.3, it was possible for an attacker to craft a malicious PDF file that causes a denial of service (DoS) by triggering large memory usage. This happens because the library sometimes ignores the MAX_DECLARED_STREAM_LENGTH setting when parsing a content stream that lacks a /Length value.

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Detection Guidance

This vulnerability in pypdf involves processing malicious PDFs that contain content streams without a /Length value, leading to excessive memory usage and potential denial-of-service.

To detect this vulnerability on your system, you can check the version of the pypdf library installed. Versions prior to 6.13.3 are vulnerable.

Suggested commands to detect the vulnerable version of pypdf:

• For Python environments, run: `pip show pypdf` or `pip list | grep pypdf` to see the installed version.
• If the version is older than 6.13.3, your system is vulnerable.

To detect malicious PDFs exploiting this vulnerability on your network or system, you can monitor for unusually high memory usage or crashes when processing PDFs with pypdf, especially those lacking /Length in content streams. However, no specific detection commands or signatures are provided in the available resources.

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Impact Analysis

The impact of this vulnerability is a denial of service (DoS) condition. An attacker can exploit it by providing a specially crafted PDF that causes the pypdf library to consume excessive memory, potentially leading to application crashes or degraded performance.

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Compliance Impact

The vulnerability in pypdf (CVE-2026-57204) allows an attacker to cause a denial-of-service (DoS) by crafting malicious PDFs that lead to excessive memory consumption. This type of vulnerability primarily impacts availability by potentially disrupting service.

There is no direct information in the provided context or resources about how this vulnerability affects compliance with common standards and regulations such as GDPR or HIPAA.

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Mitigation Strategies

To mitigate this vulnerability, upgrade the pypdf library to version 6.13.3 or later, where the issue has been fixed.

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