CVE-2026-109428

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Mistral Vibe Permission Bypass via Bash Parsing Discrepancy

Publication date: 2026-10-13

Last updated on: 2026-10-13

Assigner: VulnCheck

Description

Mistral Vibe before 2.25.5 contains a permission validation bypass vulnerability that allows attackers to execute unauthorized commands by exploiting a parsing discrepancy between tree-sitter-bash and bash in handling backslash-newline line continuations in the _extract_commands() function of bash.py. Attackers can craft a command string where tree-sitter-bash extracts only an allowlisted prefix such as cd while bash joins the line continuation into a materially different and hidden command such as a curl request, causing resolve_permission to grant ALWAYS permission while bash executes unauthorized arbitrary commands.

CVSS Scores

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Meta Information

Published

2026-10-13

Last Modified

2026-10-13

Generated

2026-10-14

AI Q&A

2026-10-14

EPSS Evaluated

N/A

NVD

CVE-2026-109428

EUVD

EUVD-2026-99221

Affected Vendors & Products

Vendor	Product	Version / Range
mistralai	mistral-vibe	0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-436	Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state.

Attack-Flow Graph

Executive Summary

Mistral Vibe before 2.25.5 has a permission bypass flaw due to differing ways tree-sitter-bash and bash parse backslash-newline line continuations. Attackers can craft commands where tree-sitter-bash sees only an allowlisted prefix like 'cd' but bash executes a hidden command like a curl request. This tricks the permission system into granting full access while running unauthorized commands.

Detection Guidance

Detecting this vulnerability requires checking the version of Mistral Vibe installed on your system. Run 'mistral-vibe --version' or inspect the package metadata to verify if the version is below 2.25.5. If you are running an affected version, review command logs for unusual command sequences involving backslash-newline line continuations that may hide unauthorized commands.

Impact Analysis

If you use Mistral Vibe before 2.25.5, attackers could execute arbitrary commands on your system with unauthorized permissions. This could lead to data theft, system compromise, or further network infiltration depending on the commands run.

Mitigation Strategies

Immediately upgrade Mistral Vibe to version 2.25.5 or later to patch the vulnerability. If upgrading is not immediately possible, restrict execution permissions for Mistral Vibe to trusted users only and monitor command outputs for unexpected network requests or file modifications.

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