Memory Corruption in GNU Emacs SVG CSS Causes DoS, Data Leak

Executive Summary

CVE-2026-6861 is a memory corruption vulnerability found in GNU Emacs versions 28.1 through 30.2. It occurs in the function svg_load_image() when Emacs processes specially crafted SVG CSS data. The issue involves an off-by-one heap buffer overflow and an uninitialized heap read caused by writing a null terminator one byte beyond the allocated buffer, leading to memory corruption.

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Detection Guidance

This vulnerability is a memory corruption issue in GNU Emacs triggered by processing specially crafted SVG CSS data. Detection would involve identifying if vulnerable versions of Emacs (28.1 through 30.2) are installed and if malicious SVG files have been opened.

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

As a general approach, you can check the installed Emacs version with the command:

• emacs --version

To detect if any suspicious SVG files have been opened or exist on the system, you might search for recently accessed SVG files using commands like:

• find /path/to/search -name '*.svg' -exec ls -l {} +
• stat <filename.svg>

However, no direct commands or tools for detecting exploitation attempts or memory corruption related to this vulnerability are provided.

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Impact Analysis

A local user could exploit this vulnerability by convincing a victim to open a malicious SVG file in GNU Emacs. Successful exploitation may lead to a denial of service (DoS), causing the application to crash, or potentially result in information disclosure due to memory corruption.

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Compliance Impact

The vulnerability in GNU Emacs could potentially lead to information disclosure if exploited, which may impact compliance with data protection regulations such as GDPR or HIPAA. However, the provided information does not specify any direct effects or compliance implications related to these standards.

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Mitigation Strategies

To mitigate this vulnerability, you should upgrade GNU Emacs to a version where the flaw is fixed. The issue was resolved upstream in Emacs version 30 with commit 8f535370b9.

If immediate upgrade is not possible, avoid opening untrusted or specially crafted SVG files in Emacs to prevent exploitation.

Additionally, applying any vendor patches or updates provided by your Linux distribution that address this vulnerability is recommended.

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