CVE-2025-64137 identifies a security vulnerability in the Jenkins Themis Plugin, versions 1.4.1 and earlier, where a missing permission check allows users with Overall/Read permissions to initiate connections from the Jenkins server to an attacker-controlled HTTP server. Jenkins is a widely used automation server for continuous integration and continuous delivery (CI/CD), and plugins like Themis extend its functionality. The vulnerability arises because the plugin does not properly verify whether the user has sufficient permissions before allowing the server to connect externally. This could be exploited by an attacker who has at least read-level access to Jenkins to cause the server to make outbound HTTP requests to malicious infrastructure. Such behavior can be leveraged for various malicious purposes, including data exfiltration, command and control communication, or triggering SSRF (Server-Side Request Forgery) style attacks. Although the vulnerability does not allow direct code execution or privilege escalation, the ability to make arbitrary outbound connections can be a stepping stone in a broader attack chain. The vulnerability is notable because Overall/Read permission is often granted to many users, including those who may not be fully trusted, thus broadening the potential attacker base. No CVSS score has been assigned yet, and no public exploits have been reported as of the publication date. The lack of patch links suggests that a fix may still be pending or in development. Organizations using Jenkins with the Themis Plugin should consider this vulnerability seriously due to the critical role Jenkins plays in software development pipelines and the potential for indirect impacts on confidentiality and integrity.

For European organizations, the impact of CVE-2025-64137 can be significant due to the widespread use of Jenkins in software development and deployment environments. The vulnerability allows attackers with relatively low privileges (Overall/Read) to cause Jenkins servers to connect to attacker-controlled HTTP servers, which can lead to data leakage, exposure of internal network details, or facilitation of further attacks such as SSRF or command and control communication. This could compromise the confidentiality of sensitive build artifacts, credentials, or internal APIs accessed by Jenkins. Additionally, it may undermine the integrity of the CI/CD pipeline if attackers use this vector to influence build processes indirectly. The availability impact is limited but could arise if attackers leverage this to disrupt Jenkins operations or cause resource exhaustion through malicious outbound connections. European organizations with complex software supply chains and regulatory requirements around data protection (e.g., GDPR) face increased risk if such vulnerabilities are exploited. The threat is particularly relevant to sectors with high software development activity, such as finance, telecommunications, and technology companies, which are prevalent in countries like Germany, France, the UK, and the Netherlands.

To mitigate CVE-2025-64137, European organizations should implement the following specific measures: 1) Audit and restrict Overall/Read permissions in Jenkins to only trusted users, minimizing the number of users who can exploit this vulnerability. 2) Monitor and control outbound HTTP connections from Jenkins servers using network-level controls such as firewalls or proxy servers to detect and block unauthorized external connections. 3) Implement strict plugin management policies, including disabling or removing the Themis Plugin if not essential, or upgrading to a patched version once available. 4) Employ Jenkins security best practices, such as using role-based access control (RBAC) plugins to enforce granular permission assignments. 5) Conduct regular security assessments and penetration testing focused on CI/CD environments to detect misuse of permissions or anomalous network activity. 6) Stay informed about updates from the Jenkins project and apply security patches promptly when released. 7) Consider isolating Jenkins servers in segmented network zones with limited outbound internet access to reduce exposure. These targeted actions go beyond generic advice by focusing on permission hygiene, network egress control, and plugin management specific to this vulnerability.