CVE-2026-87986 in Mistral Vibe
Summary
by MITRE • 09/11/2026
An arbitrary code execution vulnerability in Mistral Vibe allows an attacker to bypass command permission checks using shell constructs it's parser cannot interpret. Unparsed portions are omitted from inspection, enabling embedded commands to execute on the user's system without approval.
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Analysis
by VulDB Data Team • 09/11/2026
The identified vulnerability represents a critical security flaw within the Mistral Vibe application, classified fundamentally as an arbitrary code execution issue rooted in improper input validation and command injection mechanics. This specific weakness arises from a deficiency in how the software parses shell commands before executing them against the underlying operating system. The core technical failure lies in the parser's inability to correctly interpret certain complex or obfuscated shell constructs. When such unparsable syntax is encountered, rather than rejecting the entire input as malformed or potentially malicious, the application proceeds with execution while silently omitting the problematic portions from its security inspection routines. This behavior creates a significant blind spot where embedded commands can be hidden within syntactically ambiguous structures that evade detection by both the parser and any associated permission checks designed to restrict user actions.
From an operational perspective, this flaw allows an attacker to bypass command permission controls effectively. By crafting inputs that exploit the parsing ambiguity, malicious actors can inject arbitrary system-level commands into the execution pipeline. Since these embedded commands are not subjected to the standard approval workflows or access control lists due to their exclusion from the inspection phase, they execute with the privileges of the user running Mistral Vibe. This capability transforms a simple input field or configuration parameter into a vector for remote code execution, potentially leading to full system compromise depending on the context in which the application operates and the permissions granted to its runtime environment. The impact extends beyond mere unauthorized access; it enables data exfiltration, installation of persistent backdoors, lateral movement within networked environments, and complete loss of integrity for systems where Mistral Vibe is deployed with elevated privileges.
This vulnerability aligns closely with Common Weakness Enumeration (CWE) identifiers such as CWE-78 Improper Neutralization of Special Elements used in an OS Command, commonly known as OS Command Injection, and specifically relates to CWE-94 Improper Control of Generation of Code or Script where the code is not properly validated before execution. Furthermore, from a tactical standpoint within the MITRE ATT&CK framework, this behavior corresponds to techniques involving command and script interpretation abuse, particularly those that leverage obfuscation to evade detection mechanisms like Endpoint Detection and Response systems. The exploitation method resembles T1059 Command Line Interface Interpretation where attackers use shell metacharacters or complex syntax to bypass security filters.
Mitigation strategies must address both the immediate technical flaw and broader architectural weaknesses. Immediate remediation should involve patching the Mistral Vibe software to a version that corrects the parser logic, ensuring that all input is strictly validated against an allowlist of expected characters and structures before any processing occurs. Developers must implement strict parsing rules that reject ambiguous or complex shell constructs rather than attempting partial execution. Long-term mitigation requires adopting secure coding practices such as avoiding direct OS command invocation where possible, preferring native APIs for system interactions to eliminate the need for shell interpretation entirely. If shell commands are unavoidable, inputs should be passed as arguments to executables without invoking a shell interpreter, thereby neutralizing metacharacter exploitation vectors. Additionally, implementing robust input validation frameworks and conducting regular static and dynamic application security testing can help identify similar parsing vulnerabilities before deployment in production environments.