CVE-2025-64136 identifies a cross-site request forgery (CSRF) vulnerability in the Jenkins Themis Plugin versions 1.4.1 and earlier. Themis Plugin is used within Jenkins, a widely adopted automation server for continuous integration and continuous delivery (CI/CD). The vulnerability allows an attacker to trick an authenticated Jenkins user into executing unintended HTTP requests that cause the Jenkins server to connect to an attacker-controlled HTTP server. This can lead to unauthorized actions such as data leakage, command execution via crafted requests, or manipulation of Jenkins workflows. The attack vector relies on the victim being authenticated to Jenkins and visiting a malicious web page that triggers the CSRF. No public exploits are currently known, and no official CVSS score has been assigned. The vulnerability highlights a lack of proper CSRF protections in the plugin's HTTP request handling, enabling attackers to bypass normal security controls. Given Jenkins' role in software development pipelines, exploitation could compromise build integrity and leak sensitive project data. The vulnerability was published on October 29, 2025, shortly after being reserved, indicating recent discovery. No patches or mitigations have been officially released at the time of this report, emphasizing the need for immediate defensive measures.

For European organizations, this vulnerability poses a significant risk to the integrity and confidentiality of software development processes. Jenkins is widely used across Europe in both public and private sectors for automating builds, tests, and deployments. Exploitation could allow attackers to redirect Jenkins to attacker-controlled servers, potentially exfiltrating sensitive build artifacts, credentials, or injecting malicious code into software pipelines. This could lead to supply chain compromises, data breaches, or disruption of critical infrastructure projects. The impact is heightened in industries with stringent regulatory requirements such as finance, healthcare, and government, where Jenkins pipelines often handle sensitive data. The vulnerability could also undermine trust in automated CI/CD processes, causing operational delays and increased remediation costs. Since exploitation requires authenticated users, insider threats or phishing campaigns targeting Jenkins users could facilitate attacks. The absence of known exploits in the wild currently limits immediate risk but does not preclude future exploitation. Overall, the vulnerability threatens confidentiality, integrity, and availability of development environments in Europe.

1. Immediately audit Jenkins instances to identify usage of the Themis Plugin and its version. 2. Restrict plugin installation and usage to trusted administrators only until a patch is available. 3. Implement strict network egress filtering on Jenkins servers to prevent unauthorized outbound connections to untrusted HTTP servers. 4. Educate Jenkins users about the risks of CSRF and encourage avoidance of untrusted web content while authenticated. 5. Monitor Jenkins logs for unusual outbound HTTP connections or unexpected plugin activity. 6. Once available, promptly apply vendor patches or updates addressing the CSRF vulnerability. 7. Consider deploying web application firewalls (WAF) with CSRF protection rules tailored for Jenkins endpoints. 8. Use Jenkins security features such as CSRF protection tokens and enforce strong authentication and session management policies. 9. Isolate Jenkins servers within segmented network zones to limit exposure. 10. Regularly review and update plugin inventories and security configurations to reduce attack surface.