In JetBrains Junie CLI versions prior to 26.8.3, a configuration flaw in the MCP server setup permits an attacker who controls the configuration of an untrusted project to trigger arbitrary code execution. The vulnerability allows the execution of code within the user's environment with the same privileges as the Junie CLI process. This can be used to compromise system integrity or gain additional access if the CLI is run with elevated privileges.

The affected product is JetBrains Junie CLI. All installations of Junie CLI newer than 26.8.3 are considered unaffected. Versions earlier than 26.8.3 are susceptible to the flaw.

The vulnerability has a CVSS score of 7.8, indicating a high severity. The EPSS score is below 1%, suggesting a low probability of exploitation in the wild. It is not listed in the CISA KEV catalog. Exploitation would require the attacker to supply a malicious MCP server configuration to a trusted Junie CLI user, making the attack vector likely limited to environments where users can specify or modify project MCP server settings. The resulting impact is Remote Code Execution within the user's local context.