CVE-2025-6004 is a medium-severity vulnerability affecting HashiCorp Vault, specifically versions starting from 1.13.0 prior to the patched releases 1.20.1 (Community Edition) and 1.20.1, 1.19.7, 1.18.12, and 1.16.23 (Enterprise Editions). The vulnerability is classified under CWE-307, which pertains to improper restriction of excessive authentication attempts. In this case, Vault's user lockout feature, designed to prevent brute force attacks by locking out users after a certain number of failed login attempts, can be bypassed when using the Userpass and LDAP authentication methods. This bypass means an attacker can repeatedly attempt to authenticate without triggering the lockout mechanism, increasing the risk of successful brute force or credential stuffing attacks. The CVSS v3.1 base score is 5.3 (medium), with the vector indicating that the attack can be performed remotely (AV:N), with low attack complexity (AC:L), no privileges required (PR:N), no user interaction needed (UI:N), and impacts integrity (I:L) but not confidentiality or availability. The vulnerability does not appear to have known exploits in the wild yet. The root cause lies in insufficient enforcement of authentication attempt limits, allowing attackers to circumvent the lockout controls and potentially gain unauthorized access or degrade the integrity of authentication processes. This vulnerability affects critical components of Vault's authentication subsystem, which is central to securing secrets and sensitive data in many organizations.

For European organizations, the impact of CVE-2025-6004 can be significant, especially for those relying on HashiCorp Vault to manage secrets, credentials, and sensitive configuration data. Successful exploitation could allow attackers to perform brute force attacks on user credentials without being locked out, potentially leading to unauthorized access to Vault-protected secrets. This compromises the integrity of authentication and could cascade into broader security breaches, including unauthorized access to cloud infrastructure, databases, and internal services. Given Vault's widespread use in DevOps and cloud-native environments, exploitation could disrupt secure automation pipelines and increase the risk of data leakage or manipulation. Although the vulnerability does not directly impact confidentiality or availability, the integrity compromise in authentication mechanisms can facilitate further attacks that do. European organizations in sectors such as finance, healthcare, and critical infrastructure, which often use Vault for secret management, face heightened risks. Additionally, regulatory frameworks like GDPR impose strict requirements on protecting access to personal data, so breaches stemming from this vulnerability could lead to compliance violations and financial penalties.

To mitigate CVE-2025-6004, European organizations should promptly upgrade HashiCorp Vault to the fixed versions: Community Edition 1.20.1 or Enterprise Editions 1.20.1, 1.19.7, 1.18.12, or 1.16.23. Until upgrades are applied, organizations should consider implementing compensating controls such as: 1) Enforcing multi-factor authentication (MFA) on Vault user accounts to reduce the risk of credential compromise through brute force. 2) Monitoring authentication logs for unusual patterns of failed login attempts, especially on Userpass and LDAP methods, and triggering alerts or manual lockouts. 3) Restricting network access to Vault authentication endpoints via firewall rules or VPNs to limit exposure to potential attackers. 4) Reviewing and tightening LDAP and Userpass authentication policies, including password complexity and rotation requirements. 5) Employing rate limiting or web application firewalls (WAFs) in front of Vault to detect and block excessive authentication attempts. 6) Conducting regular security audits and penetration tests focused on authentication mechanisms. These targeted measures, combined with patching, will reduce the risk of exploitation and protect the integrity of Vault authentication.