CVE-2025-45770 identifies a vulnerability in the jwt library version 5.4.3, specifically related to weak encryption practices. The core issue revolves around the cryptographic key lengths used within the library. The vulnerability is classified under CWE-326, which pertains to the use of weak cryptographic keys. However, this CVE is disputed because the library itself does not enforce key length requirements; instead, it expects the application developers to set appropriate key lengths. This dispute is currently under review according to CNA rules, but the vulnerability remains published. The CVSS v3.1 score is 7.0, indicating a high severity level, with the vector indicating network attack vector (AV:N), high attack complexity (AC:H), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), low confidentiality and integrity impact (C:L, I:L), and high availability impact (A:H). The high availability impact suggests that exploitation could lead to denial of service or significant disruption. The lack of known exploits in the wild suggests that active exploitation has not been observed yet. The vulnerability's root cause is weak encryption, which could allow attackers to compromise the confidentiality and integrity of JWT tokens, potentially leading to unauthorized access or token forgery if weak keys are used. However, since the library leaves key length decisions to the application, the actual risk depends heavily on how developers implement and configure cryptographic keys. This makes the vulnerability somewhat conditional on usage patterns rather than an inherent flaw in the library's codebase.

For European organizations, the impact of this vulnerability could be significant, especially for those relying on the jwt library for authentication and authorization in web applications and APIs. Weak encryption in JWT tokens could allow attackers to forge tokens or decrypt sensitive information, leading to unauthorized access to systems and data breaches. The high availability impact also indicates potential for denial-of-service conditions, which could disrupt critical services. Given the widespread use of JWT in modern web applications, especially in sectors like finance, healthcare, and government services across Europe, exploitation could undermine trust and compliance with regulations such as GDPR. However, the actual impact depends on whether organizations use vulnerable versions and how they manage cryptographic keys. Organizations that enforce strong key management practices may be less affected, while those with weak or default configurations are at higher risk.

European organizations should immediately audit their use of the jwt library to determine if version 5.4.3 or similar vulnerable versions are in use. They should verify that cryptographic keys used for JWT signing and encryption meet strong security standards, including adequate key lengths and secure key generation practices. Since the vulnerability is related to weak encryption rather than a direct code flaw, enforcing strict cryptographic policies is critical. Organizations should consider upgrading to newer versions of the jwt library if available, or applying patches once released. Additionally, implementing defense-in-depth measures such as token expiration, token revocation mechanisms, and monitoring for anomalous authentication activity can reduce risk. Security teams should also educate developers on proper key management and cryptographic best practices to prevent misuse. Finally, regular penetration testing and code reviews focusing on JWT handling can help identify and remediate weaknesses before exploitation.