CVE-2025-64137 identifies a security flaw in the Jenkins Themis Plugin versions 1.4.1 and earlier, where a missing permission check allows users with Overall/Read permission to force the plugin to connect to an attacker-specified HTTP server. Jenkins is a widely used automation server for continuous integration and delivery, and plugins extend its functionality. Themis Plugin's vulnerability stems from CWE-862 (Missing Authorization), meaning that the plugin fails to verify whether the user has sufficient privileges before performing network connections. Although the attacker needs only read-level access, which is a relatively low privilege, the vulnerability requires user interaction (UI:R) to be exploited. The CVSS score of 4.3 (medium) reflects that the attack vector is network-based with low attack complexity and no privileges required beyond read access, but the impact on confidentiality is none, integrity is low, and availability is unaffected. The vulnerability could be leveraged to cause the Jenkins server to interact with malicious servers, potentially leading to indirect attacks such as SSRF (Server-Side Request Forgery), information leakage, or pivoting within the network. No patches or known exploits are currently available, so organizations must rely on compensating controls until fixes are released.

For European organizations, this vulnerability poses a moderate risk primarily in environments where Jenkins is used extensively for CI/CD pipelines, especially in sectors like finance, manufacturing, and critical infrastructure. Attackers with read access could exploit this flaw to induce Jenkins servers to connect to malicious endpoints, potentially exposing internal network details or enabling further attacks such as SSRF or lateral movement. While the vulnerability does not directly compromise data confidentiality, the integrity of build processes could be undermined if attackers manipulate network interactions. The requirement for at least read permission and user interaction limits the attack surface but does not eliminate risk, especially in large organizations with many users. The impact is heightened in organizations with less stringent access controls or monitoring. Disruption to automated build and deployment processes could also affect operational continuity.

European organizations should immediately audit and restrict Jenkins user permissions, ensuring that only trusted users have Overall/Read access to the Themis Plugin. Network-level controls should be implemented to restrict outbound HTTP connections from Jenkins servers to only trusted destinations, effectively preventing connections to attacker-controlled servers. Monitoring and logging of Jenkins plugin network activity can help detect anomalous connections indicative of exploitation attempts. Until an official patch is released, consider disabling or uninstalling the Themis Plugin if it is not essential. Additionally, enforce multi-factor authentication and strict access controls on Jenkins instances to reduce the risk of unauthorized access. Regularly review plugin versions and subscribe to Jenkins security advisories to apply updates promptly once available.