Yamcs is a mission control framework. Prior to 5.12.7, the authentication endpoint POST /auth/token in yamcs-core, handled by yamcs-core/src/main/java/org/yamcs/http/auth/AuthHandler.java, lacked any rate limiting, account lockout, or failed-attempt throttling, so an unauthenticated remote attacker could perform unlimited password-guessing attempts against any user account, significantly increasing the risk of successful brute-force attacks. This issue is fixed in versions 5.12.7 and 5.13.0.

Affected: Maven: org.yamcs:yamcs-core

### Summary

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.

### Root Cause

**File:** `yamcs-core/src/main/java/org/yamcs/http/auth/AuthHandler.java`

`POST /auth/token` has no rate limiting, no lockout after failed attempts, and no CAPTCHA. The handler processes unlimited authentication requests without any throttling mechanism:

```java // AuthHandler.java — handleToken() // No throttle, no failed attempt counter, no lockout private void handleToken(HandlerContext ctx) { ... getSecurityStore().login(token).whenComplete((info, err) -> { // Directly attempts authentication with no rate check }); } ```

This is absent by default — the official quickstart and documentation contain no guidance on configuring rate limiting.

### Impact

An attacker can make unlimited authentication attempts against any account. This enables efficient brute-force attacks against any account.

### Proof of Concept

```bash # 20 attempts — zero rate limiting for i in $(seq 1 20); do curl -s -o /dev/null -w "Attempt $i: HTTP %{http_code}\n" \ -X POST "http://TARGET:8090/auth/token" \ -d "grant_type=password&username=operator&password=op…