Advisories for Maven/Org.yamcs/Yamcs-Core package

2026

Yamcs vulnerable to unauthorized user enumeration via IAM API endpoints

The IAM API endpoints (listUsers, getUser, listGroups, and getGroup) in yamcs-core do not enforce the required SystemPrivilege.ControlAccess check. As a result, any authenticated user (even those with low or no privileges) can enumerate all user accounts in the system, including their usernames, superuser status, and group memberships. This constitutes a broken access control vulnerability (CWE-862) that leaks sensitive user information.

Yamcs Vulnerable to Server-Side Code Injection (RCE) via Janino Expression Engine in `JavaExprAlgorithmExecutionFactory`

A Server-Side Code Injection vulnerability exists in the Yamcs algorithm evaluation engine (org.yamcs.algorithms.JavaExprAlgorithmExecutionFactory). The application dynamically compiles and evaluates user-controlled algorithm text without enforcing a secure sandbox. An authenticated user with the ChangeMissionDatabase privilege can exploit this to achieve Remote Code Execution (RCE) on the underlying host operating system via the Janino compiler.

Yamcs Vulnerable to Remote Code Execution via Mission Database algorithm override

The Nashorn ScriptEngine used to evaluate user-supplied algorithm text in MdbOverrideApi.updateAlgorithm is constructed without a ClassFilter, allowing a user with the ChangeMissionDatabase privilege to execute arbitrary Java code on the Yamcs server. In Yamcs's default configuration (no security.yaml), the built-in guest user has superuser=true, so the vulnerability is reachable without authentication.

Yamcs Vulnerable to Authenticated Remote Code Execution (RCE) via Jython Algorithm Code Injection

A Server-Side Code Injection vulnerability exists in the Yamcs script evaluation engine for Python algorithms. The application dynamically compiles and evaluates user-controlled algorithm text using Jython (via the JSR-223 ScriptEngine API) without enforcing a secure sandbox. An authenticated user with the ChangeMissionDatabase privilege can exploit this by overriding the algorithm logic through the REST API, achieving Remote Code Execution (RCE) on the underlying host operating system.

Yamcs has No Rate Limiting on Authentication Endpoint

The authentication endpoint POST /auth/token in yamcs-core lacks any form of rate limiting, account lockout, or failed attempt throttling. As a result, an unauthenticated remote attacker can perform unlimited password guessing attempts against any user account. This missing rate limiting vulnerability (CWE-307) significantly increases the risk of successful brute-force attacks.