CVE-2024-25718 is a critical vulnerability affecting the Samly package for the Elixir programming language, specifically versions prior to 1.4.0. The vulnerability arises from the function Samly.State.Store.get_assertion/3, which can return an expired session token. This occurs because the Samly.AuthHandler component caches session assertions and does not replace or refresh them even after they have expired. As a result, access control mechanisms relying on these cached sessions can be bypassed, allowing unauthorized access to protected resources. The core issue is a failure to properly invalidate or refresh session tokens upon expiry, leading to a scenario where stale authentication data is accepted as valid. This flaw impacts the confidentiality and integrity of applications using the affected Samly versions, as attackers could exploit expired sessions to gain unauthorized access without needing to re-authenticate. The vulnerability has a CVSS v3.1 base score of 9.1, indicating a critical severity level. It requires no privileges and no user interaction to exploit, and can be triggered remotely over the network. The weakness is classified under CWE-400, which relates to uncontrolled resource consumption, but in this context it reflects improper session management leading to security bypass. Although no known exploits are currently reported in the wild, the high severity and ease of exploitation make it a significant threat to applications relying on Samly for authentication and session management in Elixir environments.

For European organizations, the impact of CVE-2024-25718 can be substantial, especially for those developing or deploying web applications and services using the Elixir language with the Samly package for SAML-based authentication. The vulnerability undermines access control, potentially allowing attackers to access sensitive data, perform unauthorized actions, or escalate privileges by leveraging expired session tokens. This can lead to data breaches, intellectual property theft, and disruption of business operations. Sectors such as finance, healthcare, government, and critical infrastructure, which often employ strict access controls and rely on SAML for federated identity management, are particularly at risk. The breach of confidentiality and integrity could also result in regulatory non-compliance under GDPR and other European data protection laws, leading to legal and financial penalties. Additionally, the vulnerability could be exploited to move laterally within networks, increasing the risk of broader compromise. Given the critical CVSS score and the fact that exploitation does not require authentication or user interaction, the threat poses a high risk to European organizations using affected software components.

To mitigate CVE-2024-25718, European organizations should take the following specific actions: 1) Immediately upgrade the Samly package to version 1.4.0 or later, where the session expiration handling has been corrected. 2) Audit all applications and services using Samly for authentication to identify affected versions and deployment points. 3) Implement additional session validation layers where possible, such as server-side session expiration checks independent of the Samly cache. 4) Monitor authentication logs for unusual access patterns indicative of session reuse or bypass attempts. 5) Employ short session lifetimes and enforce re-authentication policies to limit the window of opportunity for exploiting expired sessions. 6) Where feasible, integrate multi-factor authentication (MFA) to reduce the risk of unauthorized access through session token misuse. 7) Conduct penetration testing focused on session management to verify that expired sessions are properly invalidated. 8) Coordinate with development teams to review and improve session caching mechanisms to ensure they respect token expiry semantics. These measures go beyond generic advice by focusing on the specific caching and session handling flaws in Samly and emphasizing proactive detection and layered defense.