CVE-2024-4629 is a vulnerability identified in Keycloak version 24.0.3 that stems from improper enforcement of a single, unique action related to brute force protection mechanisms. Keycloak is an open-source identity and access management solution widely used for authentication and authorization. The flaw allows attackers to bypass the intended brute force protection by exploiting the timing of login attempts. Specifically, when multiple login requests are initiated simultaneously, the system fails to correctly count these attempts against the configured threshold for failed logins before locking out the user or IP. This timing loophole means attackers can make more password guesses than the system intends to allow, increasing the risk of successful credential guessing attacks. The vulnerability does not require any prior authentication or user interaction, making it remotely exploitable over the network. The CVSS 3.1 base score is 6.5 (medium severity), reflecting the network attack vector, low attack complexity, no privileges or user interaction required, and partial impact on confidentiality and integrity. Although no known exploits are reported in the wild yet, the vulnerability poses a significant risk to account security on affected Keycloak deployments. Since Keycloak is often deployed in enterprise and government environments for critical identity services, exploitation could lead to unauthorized access to sensitive applications and data. The vulnerability was reserved in May 2024 and published in September 2024, with no patch links currently provided, indicating that remediation may require close monitoring of vendor updates or applying custom mitigations.

For European organizations, this vulnerability presents a tangible risk to the security of user accounts managed through Keycloak, potentially leading to unauthorized access to internal systems, sensitive data, and critical applications. Organizations relying on Keycloak for single sign-on (SSO) or identity federation could see increased exposure to credential stuffing or brute force attacks that bypass existing lockout policies. This could result in data breaches, compliance violations (e.g., GDPR), and operational disruptions. Public sector entities and large enterprises using Keycloak for identity management are particularly at risk, as attackers may target these high-value environments. The medium severity rating reflects that while the vulnerability does not directly cause denial of service or full system compromise, it undermines a key security control, increasing the likelihood of successful account compromise. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits following public disclosure. The impact is heightened in environments where multi-factor authentication (MFA) is not enforced, as brute force attacks become more feasible.

European organizations should take proactive steps to mitigate this vulnerability even before an official patch is available. Specific recommendations include: 1) Implement network-level rate limiting and throttling on authentication endpoints to prevent rapid, simultaneous login attempts from the same source or IP range. 2) Deploy Web Application Firewalls (WAFs) with rules designed to detect and block brute force patterns and concurrent login attempts. 3) Enable and enforce multi-factor authentication (MFA) to reduce the risk of account compromise even if password guessing succeeds. 4) Monitor authentication logs for unusual spikes in failed login attempts or simultaneous requests from single accounts or IPs. 5) Consider temporarily increasing lockout sensitivity or reducing allowed failed attempts while monitoring for false positives. 6) Stay informed on Keycloak vendor advisories and apply patches promptly once released. 7) If feasible, implement custom patches or workarounds that serialize login attempts or improve enforcement of unique action constraints. 8) Educate users about strong password policies and phishing risks to complement technical controls.