CVE-2025-64131 identifies a security weakness in the Jenkins SAML Plugin, specifically in versions up to 4.583.vc68232f7018a_. The vulnerability stems from the plugin's failure to implement a replay cache mechanism during the SAML authentication process. SAML (Security Assertion Markup Language) is widely used for single sign-on (SSO) authentication, where assertions are exchanged between an identity provider and a service provider (in this case, Jenkins). Without a replay cache, an attacker who can intercept or obtain information about the SAML authentication flow can replay previously captured authentication requests. This replay attack allows the attacker to impersonate legitimate users and gain unauthorized access to Jenkins. Since Jenkins is a popular automation server used in continuous integration and continuous deployment (CI/CD) pipelines, unauthorized access could lead to codebase manipulation, pipeline sabotage, or exposure of sensitive build and deployment information. The vulnerability does not require user interaction beyond the attacker’s ability to observe or intercept SAML messages, and no authentication is needed to exploit the replay once the data is captured. Although no public exploits are currently known, the risk is significant given the critical nature of Jenkins in software development workflows. The lack of a CVSS score suggests the vulnerability is newly disclosed, and the severity assessment must consider the potential impact on confidentiality, integrity, and availability of Jenkins environments.

For European organizations, the impact of CVE-2025-64131 can be substantial. Jenkins is extensively used across Europe in software development, particularly in industries such as finance, automotive, telecommunications, and government sectors. Unauthorized access to Jenkins via replay attacks could lead to unauthorized code changes, insertion of malicious code, disruption of automated build and deployment processes, and leakage of sensitive intellectual property or credentials stored in Jenkins. This could result in operational downtime, reputational damage, regulatory non-compliance (e.g., GDPR breaches if personal data is exposed), and financial losses. The vulnerability undermines trust in the authentication mechanism, potentially allowing attackers to bypass multi-factor authentication if it relies solely on SAML assertions. The risk is heightened in environments where network traffic is not adequately protected, such as in hybrid or cloud deployments without strict network segmentation or encryption. European organizations with stringent security and compliance requirements must prioritize addressing this vulnerability to prevent exploitation that could compromise critical development infrastructure.

To mitigate CVE-2025-64131, organizations should: 1) Monitor Jenkins SAML Plugin updates closely and apply patches immediately once available from the Jenkins Project to ensure replay cache or equivalent protections are implemented. 2) Until patched, restrict network access to Jenkins servers to trusted networks and use VPNs or zero-trust network architectures to prevent interception of SAML authentication flows. 3) Employ TLS encryption rigorously for all communications between users, identity providers, and Jenkins to reduce the risk of interception. 4) Implement additional authentication layers such as multi-factor authentication (MFA) at the identity provider level to reduce the impact of replayed assertions. 5) Conduct regular audits of Jenkins access logs to detect suspicious authentication patterns indicative of replay attacks. 6) Consider deploying Web Application Firewalls (WAFs) or Intrusion Detection Systems (IDS) with rules to detect and block replayed SAML requests. 7) Educate DevOps and security teams about the risks of SAML replay attacks and the importance of timely patching and network security controls. 8) Review and harden identity provider configurations to limit assertion validity periods and enforce strict session management policies.