Buffer Overflow in iconv Encoding Modules

Executive Summary

CVE-2026-58081 is a buffer overflow vulnerability in the iconv(3) function. Several encoding modules (HZ, UTF-7, VIQR, and ZW) fail to check the output buffer size before writing converted characters. This can lead to buffer overflows when processing untrusted input with these encodings.

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Detection Guidance

To detect this vulnerability, check if your system uses iconv(3) with affected encodings (HZ, UTF-7, VIQR, ZW). Run 'pkg audit' to see if vulnerable versions are installed. Check running processes with 'ps aux | grep iconv' to identify applications using iconv.

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Impact Analysis

Applications using iconv(3) to convert untrusted input with affected encodings may be vulnerable to buffer overflows. This could allow attackers to execute arbitrary code, crash the application, or gain unauthorized access to the system.

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Compliance Impact

This vulnerability could lead to buffer overflows in applications processing untrusted input with affected encodings. Such flaws may allow arbitrary code execution, potentially compromising data integrity and confidentiality. This could violate compliance requirements under GDPR (data protection) and HIPAA (health data security) by enabling unauthorized access or data breaches.

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Mitigation Strategies

Upgrade your system immediately using 'pkg update && pkg upgrade' or 'freebsd-update fetch install'. Apply source patches if available. Restart all applications using iconv or reboot the system to ensure changes take effect.

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