CVE-2024-21662

An attacker can effectively bypass the rate limit and brute force protections by exploiting the application's weak cache-based mechanism. This loophole in security can be combined with other vulnerabilities to attack the default admin account. This flaw undermines a previously patched CVE intended to protect against brute-force attacks.

Details

The application's brute force protection relies on a cache mechanism that tracks login attempts for each user. This cache is limited to a defaultMaxCacheSize of 1000 entries. An attacker can overflow this cache by bombarding it with login attempts for different users, thereby pushing out the admin account's failed attempts and effectively resetting the rate limit for that account.

The brute force protection mechanism's code:

   if failed && len(failures) >= getMaximumCacheSize() {
       log.Warnf("Session cache size exceeds %d entries, removing random entry",

getMaximumCacheSize())
       idx := rand.Intn(len(failures) - 1)
       var rmUser string
       i := 0
       for key := range failures {

           if i == idx {
               rmUser = key

               delete(failures, key)

break

}

i++ }

       log.Infof("Deleted entry for user %s from cache", rmUser)
   }

PoC

1. Set up the application environment and identify the login page.
2. Execute 4 failed login attempts for the admin account.
3. Run a Burp Intruder attack to populate the cache with login attempts for usernames ranging from 1 to 10000.
4. After 1000 attempts, start monitoring to see if the admin entries in the cache have been cleared.
5. At this point, brute-force the admin account.

In just 15 minutes, the PoC was able to perform 230 brute force attempts on the admin account. This rate allows for approximately 1000 requests per hour, effectively rendering the older CVE rate limit patches useless.

This is a severe vulnerability that enables attackers to perform brute force attacks at an accelerated rate, especially targeting the default admin account.

CVE-2024-21662 has a CVSS score of 5.4 (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 (2.8.13, 2.9.9, 2.10.4); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2024-21662? CVE-2024-21662 is a medium-severity security vulnerability in github.com/argoproj/argo-cd/v2 (go), affecting versions < 2.8.13. It is fixed in 2.8.13, 2.9.9, 2.10.4.
2. How severe is CVE-2024-21662? CVE-2024-21662 has a CVSS score of 5.4 (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 github.com/argoproj/argo-cd/v2 are affected by CVE-2024-21662? github.com/argoproj/argo-cd/v2 (go) versions < 2.8.13 is affected.
4. Is there a fix for CVE-2024-21662? Yes. CVE-2024-21662 is fixed in 2.8.13, 2.9.9, 2.10.4. Upgrade to this version or later.
5. Is CVE-2024-21662 exploitable, and should I be worried? Whether CVE-2024-21662 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-2024-21662 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-2024-21662?
   • Upgrade github.com/argoproj/argo-cd/v2 to 2.8.13 or later
   • Upgrade github.com/argoproj/argo-cd/v2 to 2.9.9 or later
   • Upgrade github.com/argoproj/argo-cd/v2 to 2.10.4 or later