Impact Analysis

The impact of this vulnerability is limited, as indicated by the CVSS base score of 3.7.

It does not affect confidentiality or availability, but it can lead to a low impact on integrity, potentially allowing malformed URLs to be processed incorrectly.

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Executive Summary

This vulnerability exists in the mutt email client versions before 2.3.2, where the function url_pct_decode does not check for embedded null characters ('\0') in URLs.

Specifically, the function fails to consider the URL-encoded null byte (%00) as an invalid character, which can lead to improper handling of URLs.

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Detection Guidance

This vulnerability involves the presence of embedded null characters (%00) in URLs processed by the mutt email client before version 2.3.2. Detection would involve identifying URLs containing the URL-encoded null byte (%00) in email traffic or configuration files used by mutt.

You can search for such patterns in email files or logs using commands like:

• grep -r '%00' /path/to/email/files
• tcpdump -A -s 0 'tcp port 25' | grep '%00'
• Alternatively, review mutt configuration or scripts that handle URLs for the presence of %00 sequences.

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Mitigation Strategies

The immediate mitigation step is to upgrade the mutt email client to version 2.3.2 or later, where the url_pct_decode() function has been patched to reject URLs containing the %00 (null byte) character.

Until the upgrade is applied, avoid processing or opening emails containing suspicious URLs with embedded null characters.

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Compliance Impact

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

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