CVE-2026-84663 in Groovy Libraries Plugin
Summary
by MITRE • 09/02/2026
A cross-site request forgery (CSRF) vulnerability in Jenkins Pipeline: Groovy Libraries Plugin 798.v5cc688825312 and earlier allows attackers to delete shared library caches.
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Analysis
by VulDB Data Team • 09/02/2026
The Jenkins Pipeline: Groovy Libraries Plugin, specifically versions up through 798.v5cc688825312, contains a critical cross-site request forgery vulnerability that impacts the integrity of pipeline execution environments by allowing unauthorized deletion of shared library caches. This plugin is designed to facilitate the management and loading of reusable code libraries within Jenkins pipelines, enabling teams to maintain consistent coding standards and reduce duplication across multiple projects. The underlying flaw stems from insufficient validation of incoming requests regarding their origin or authenticity, a classic oversight in web application security that permits malicious actors to trick authenticated administrators into performing actions they did not intend. In this specific context, the vulnerability targets the administrative endpoints responsible for managing cached Groovy library artifacts, which are essential components stored locally on the Jenkins server to accelerate pipeline execution and ensure version consistency across builds.
From a technical perspective, the absence of anti-CSRF tokens or equivalent state-changing request validation mechanisms allows an attacker to craft malicious web pages that automatically submit requests to the vulnerable Jenkins instance when visited by an authenticated user with sufficient privileges. When such a user interacts with the compromised page while logged into their Jenkins session, the browser automatically includes valid authentication cookies and credentials in the forged request. This results in the successful execution of commands intended only for authorized administrators, specifically those that clear or delete shared library caches without any explicit confirmation or security challenge from the system. The vulnerability exploits the trust relationship between the web application and the user's browser, leveraging the fact that browsers do not distinguish between requests initiated by the user directly versus those triggered programmatically via malicious scripts embedded in third-party sites.
The operational impact of this vulnerability is significant for organizations relying on Jenkins for continuous integration and delivery workflows. By deleting shared library caches, an attacker can effectively disrupt pipeline executions, causing builds to fail or behave unpredictably as they attempt to load libraries that are no longer available locally. This denial-of-service effect forces the system to re-fetch libraries from remote repositories, increasing latency and potentially exposing sensitive repository credentials if not properly secured. Furthermore, in more sophisticated attack scenarios, an attacker could manipulate the state of cached libraries by combining this deletion with other injection techniques or timing attacks to introduce malicious code during subsequent library downloads, thereby compromising the integrity of the entire software supply chain managed through Jenkins. This undermines the reliability and security posture of development teams who depend on automated builds for production deployments.
This vulnerability aligns closely with CWE-352, which defines cross-site request forgery as a weakness where a site accepts requests from untrusted sources without proper validation. Additionally, it maps to MITRE ATT&CK technique T1078, specifically the aspect of valid accounts being used for malicious purposes through social engineering or automated exploitation via web interfaces. The lack of robust input validation and session management controls represents a fundamental security design flaw that violates best practices outlined in OWASP guidelines for preventing CSRF attacks. Organizations must recognize that even administrative functions involving cache management are high-value targets because they directly affect the availability and consistency of development infrastructure.
To mitigate this risk, immediate action is required to upgrade the Jenkins Pipeline: Groovy Libraries Plugin to a version later than 798.v5cc688825312 where these security controls have been implemented. If upgrading is not immediately feasible, administrators should implement network-level restrictions such as restricting access to Jenkins instances from untrusted networks and ensuring that CSRF protection mechanisms are enabled at the application level or through reverse proxy configurations like Nginx or Apache if supported by the deployment architecture. Additionally, enforcing strict Content Security Policy headers can help mitigate some aspects of script injection that facilitate CSRF attacks. Regular security audits and penetration testing should be conducted to identify similar vulnerabilities in other plugins and core Jenkins components, ensuring a comprehensive defense-in-depth strategy against web-based application threats.