CVE-2021-21620 in Claim Plugin
Summary
by MITRE • 02/24/2021
A cross-site request forgery (CSRF) vulnerability in Jenkins Claim Plugin 2.18.1 and earlier allows attackers to change claims.
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Analysis
by VulDB Data Team • 02/24/2021
Cross-site request forgery vulnerabilities represent a critical class of web application security flaws that allow attackers to perform unauthorized actions on behalf of authenticated users. The Jenkins Claim Plugin vulnerability affects versions 2.18.1 and earlier, where the plugin fails to implement proper anti-CSRF protection mechanisms. This flaw enables malicious actors to craft specially crafted requests that can manipulate claim data within the Jenkins environment without user consent or knowledge.
The technical implementation of this CSRF vulnerability stems from the absence of valid anti-CSRF tokens in the plugin's web forms and API endpoints. When users navigate to compromised pages or click on malicious links, the browser automatically submits requests to the Jenkins server with the victim's authentication cookies. The Claim Plugin does not validate that requests originate from legitimate user interactions within the application context, making it susceptible to exploitation through techniques such as iframe-based attacks, hidden form submissions, or crafted malicious websites that leverage the victim's authenticated session.
The operational impact of this vulnerability extends beyond simple data modification, as claims in Jenkins typically represent important project status indicators, build results, or quality metrics that teams rely upon for decision-making processes. Attackers could potentially manipulate build claims to hide failures, alter test results, or modify project status information, leading to cascading effects throughout continuous integration and deployment pipelines. This manipulation could deceive development teams into making incorrect decisions based on falsified data, potentially resulting in production deployments of faulty code or delayed responses to genuine issues.
Security professionals should recognize this vulnerability as a direct violation of the principle of least privilege and proper session management practices. The lack of CSRF protection aligns with CWE-352, which categorizes cross-site request forgery as a fundamental web application security weakness requiring robust token-based validation mechanisms. Organizations implementing Jenkins environments should immediately upgrade to versions beyond 2.18.1 where the vulnerability has been addressed through proper implementation of anti-CSRF token generation and validation.
Mitigation strategies must include immediate patching of affected systems, along with comprehensive review of all Jenkins plugins for similar CSRF vulnerabilities. Administrators should implement additional security layers such as content security policies, proper session management configurations, and network-level protections to reduce attack surface. Regular security assessments of web applications and automated scanning tools can help identify similar issues in other components of the CI/CD infrastructure. The vulnerability also highlights the importance of following ATT&CK framework principles for defensive measures, particularly in the context of privilege escalation and credential exposure techniques that attackers might employ through such CSRF flaws.
Organizations should conduct thorough impact assessments to determine if any unauthorized modifications have occurred due to this vulnerability during the period when affected versions were in use. The remediation process requires not only software updates but also staff training on recognizing potential CSRF attack vectors and implementing proper security monitoring procedures. Regular vulnerability scanning and penetration testing of Jenkins environments should be conducted to identify and address similar weaknesses in other plugins or custom-developed components that may expose the same class of vulnerabilities through insufficient input validation and missing anti-CSRF protections.