Executive Summary

CVE-2026-33646 is a critical vulnerability in the mise tool versions before 2026.3.10 that allows arbitrary code execution. The issue occurs because mise processes .tool-versions files using the Tera template engine, which includes the exec() function for command execution. Unlike .mise.toml files, .tool-versions files do not undergo trust verification in non-paranoid mode.

An attacker can place a malicious .tool-versions file containing Tera template syntax with embedded commands in a git repository. When a victim with mise activated enters the directory, the shell hook automatically parses and executes these commands silently without any user prompt, granting the attacker full user privileges.

This vulnerability enables silent remote code execution (RCE) with no user interaction, making it a severe supply chain attack vector.

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Impact Analysis

This vulnerability can have severe impacts including arbitrary command execution on your system with your user privileges when you enter a directory containing a malicious .tool-versions file.

Because the commands execute silently and automatically, attackers can steal credentials, tokens, or escalate privileges without your knowledge.

It poses a high risk to confidentiality, integrity, and availability of your system and data, as reflected by its critical CVSS score of 9.6.

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Mitigation Strategies

To mitigate this vulnerability, you should upgrade mise to version 2026.3.10 or later, where the issue is fixed.

The fix involves adding trust checks to the parsing of .tool-versions files, removing the exec() function from the Tera template context, or eliminating Tera processing for .tool-versions files entirely.

Until you can upgrade, avoid cds into directories containing untrusted .tool-versions files, especially those from git repositories, to prevent arbitrary command execution.

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