CVE-2025-53960 is a cryptographic vulnerability classified under CWE-1240, affecting Apache StreamPark versions from 2.0.0 before 2.1.7. The core issue is the insecure use of the user's password as the HMAC signing key for JWT issuance, specifically with the HS256 algorithm. JWTs are widely used for authentication and authorization, relying on secure signing keys to ensure token integrity and authenticity. By using the password directly as the signing key, the system exposes itself to offline brute-force attacks: an attacker who obtains a JWT can attempt to guess the password by validating the token signature offline, bypassing rate limits or detection mechanisms. This significantly lowers the barrier to password recovery compared to traditional online attacks. Furthermore, if the attacker already knows the password, they can forge arbitrary JWTs, effectively impersonating the user and gaining full account access. The vulnerability does not impact token integrity or availability directly but compromises confidentiality and authentication trust. The CVSS v3.1 score is 5.9 (medium), reflecting network attack vector, no privileges required, no user interaction, but high attack complexity. The vulnerability was publicly disclosed on December 12, 2025, and fixed in Apache StreamPark version 2.1.7. No known exploits are reported in the wild yet, but the risk remains significant due to the nature of the flaw and the widespread use of JWTs in modern authentication systems.

For European organizations, this vulnerability poses a significant risk to user credential confidentiality and authentication integrity. Compromise of user passwords through offline brute-force attacks can lead to unauthorized access to sensitive systems and data, especially in environments where Apache StreamPark is used for data streaming and processing. The ability to forge identity tokens allows attackers to bypass authentication controls, potentially leading to account takeover, data exfiltration, and lateral movement within networks. Organizations in sectors with strict data protection regulations, such as finance, healthcare, and critical infrastructure, face heightened risks of regulatory penalties and reputational damage if exploited. Additionally, the offline nature of the attack makes detection difficult, increasing the likelihood of prolonged undetected compromise. The medium severity rating suggests a moderate but non-negligible threat that should be addressed promptly to maintain security posture.

1. Upgrade Apache StreamPark to version 2.1.7 or later immediately, as this version includes a fix that replaces the insecure use of passwords as HMAC keys. 2. Review and audit all JWT implementations within the environment to ensure that cryptographic keys are generated securely and are not derived directly from user passwords. 3. Implement strong password policies and encourage the use of multi-factor authentication (MFA) to reduce the impact of password compromise. 4. Monitor authentication logs and JWT usage patterns for anomalies that may indicate token forgery or brute-force attempts. 5. Educate developers and security teams on secure cryptographic practices, emphasizing the importance of using dedicated, high-entropy keys for token signing rather than user credentials. 6. Conduct regular penetration testing and code reviews focusing on authentication mechanisms to detect similar cryptographic weaknesses. 7. If upgrading immediately is not feasible, consider implementing compensating controls such as limiting JWT lifetimes and enforcing strict token validation rules to reduce the attack window.