Dash printf Unicode Escape Memory Corruption

Executive Summary

CVE-2026-102474 is a flaw in the dash shell where the printf builtin reserves only four bytes for Unicode escape sequences like \u or \U. These sequences can require five or six bytes, causing a heap out-of-bounds write when a local user supplies such an escape to dash printf, echo %b, or dash -c with a positional argument.

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Detection Guidance

To detect this vulnerability, check if your system uses an affected version of dash. Run 'dash --version' to identify the shell version. If dash is installed, inspect whether it is the default shell or used in scripts. Look for processes using dash, especially those handling user input like printf or echo %b. Commands like 'ps aux | grep dash' or 'lsof | grep dash' may help identify usage patterns.

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Impact Analysis

This vulnerability could allow a local attacker to corrupt heap memory, potentially causing crashes or unexpected behavior in the dash shell. It does not directly escalate privileges but may lead to memory corruption or application instability if exploited.

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Compliance Impact

This vulnerability does not directly impact compliance with GDPR or HIPAA as it does not involve unauthorized data access, disclosure, or loss of availability. The flaw primarily causes memory corruption through heap out-of-bounds writes, which could lead to crashes or unexpected behavior but does not inherently violate data protection requirements under these standards.

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Mitigation Strategies

Avoid passing untrusted data into dash printf, echo %b, or dash -c commands. Update dash to a patched version if available. If dash is not the default shell, consider removing it or restricting its use. Monitor system logs for crashes or memory corruption errors that may indicate exploitation attempts.

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