CVE-2026-109429 (CVSS 8.8)

Description

Mistral Vibe before 2.25.4 contains a command permission gate bypass vulnerability that allows attackers to execute arbitrary commands by hiding a command substitution inside a single-quoted variable value that tree-sitter-bash static parsing cannot detect. Attackers can craft input such as embedding a command substitution within a single-quoted variable and re-expanding it with the ${var@P} prompt-transform operator so bash's promptvars feature executes the hidden command at runtime while only the trailing allowlisted command is classified, resulting in silent arbitrary command execution with the privileges of the agent's terminal session.

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CVSS v3.1 Score

8.8

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0056

Probability of exploitation

0.46%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-436 CWE-436

References

Other References

https://github.com/mistralai/mistral-vibe/commit/19b5b74faa78d0816b8d4d4c7d7543fc3520678c https://github.com/mistralai/mistral-vibe/pull/1084 https://github.com/mistralai/mistral-vibe/releases/tag/v2.25.4 https://www.vulncheck.com/advisories/mistral-vibe-bash-permission-bypass-via-var-p-prompt-transform

Frequently Asked Questions

What is CVE-2026-109429? +

Mistral Vibe before 2.25.4 contains a command permission gate bypass vulnerability that allows attackers to execute arbitrary commands by hiding a command substitution inside a single-quoted variable value that tree-sitter-bash static parsing cannot detect. Attackers can craft input such as embedding a command substitution within a single-quoted variable and re-expanding it with the ${var@P} prompt-transform operator so bash's promptvars feature executes the hidden command at runtime while only the trailing allowlisted command is classified, resulting in silent arbitrary command execution with the privileges of the agent's terminal session. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-109429? +

CVE-2026-109429 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0056, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-109429? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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