# CVE-2026-87984: Mistral Vibe arbitrary file write via unvalidated shell redirects

Source: https://junglewise.ai/threats/cve-2026-87984-mistral-vibe-arbitrary-file-write-via-unvalidated-shell-redirects  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-11. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-87984 · Severity: info · CVSS 9.3 · Published 2026-09-11

Mistral Vibe is an AI-powered assistant for developers that can execute bash commands with workspace-based permission controls. A vulnerability in versions 1.3.4 and later allows attackers to create or overwrite files anywhere on the system by using shell redirects (e.g., `echo "pwned" > /tmp/pwned`) with allowlisted commands, bypassing workspace permission checks. An attacker could modify source code, corrupt configuration files, establish persistence, or achieve code execution with the privileges of the Vibe process.

Technologies: [Mistral Vibe](https://junglewise.ai/threats/technologies/vibe). Vendors: [Mistral](https://junglewise.ai/threats/vendors/mistral).

## Quick answers

**Is CVE-2026-87984 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-87984 being exploited in the wild.

**How severe is CVE-2026-87984?** Informational severity, with a CVSS score of 9.3, published 11 September 2026.

**Which products and versions are affected?** Mistral Vibe 1.3.4 and later.

**Is there a fix for CVE-2026-87984?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-87984 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-87984?** Check whether you run Mistral Vibe at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

This is a path traversal vulnerability (CWE-22) where Mistral Vibe fails to validate shell redirection targets when performing permission checks. The vulnerability stems from the _extract_commands() function, which does not extract file_redirect nodes from the bash AST before reconstructing the command for permission checking. Allowlisted commands are approved for execution, but when a bash redirect is included in the original user input (e.g., `echo "pwned" > /tmp/pwned`), the redirect destination is never passed to _collect_outside_dirs() for validation. As a result, the permission check sees only the allowlisted command (`echo`) and grants approval automatically, while bash still receives and executes the full original input with the unvalidated redirect, allowing writes to arbitrary paths accessible to the Vibe process. No user approval is required, and the vulnerability is trivial to exploit—a simple redirect appended to any allowlisted command bypasses workspace protections. Patches should be available from Mistral AI.

## Affected products

- Mistral Vibe 1.3.4 and later

## Timeline

- 2026-09-11: disclosed
- 2026-09-11: advisory

## References

- [https://www.hiddenlayer.com/sai-security-advisory/2026-09-mistral-vibe2](https://www.hiddenlayer.com/sai-security-advisory/2026-09-mistral-vibe2)

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