CVE-2026-23960 is a stored cross-site scripting (XSS) vulnerability classified under CWE-79 affecting Argo Workflows, a container-native workflow engine widely used for orchestrating parallel jobs on Kubernetes clusters. The vulnerability arises from improper neutralization of input during web page generation in the artifact directory listing feature. Specifically, malicious JavaScript code can be injected by any workflow author into the artifact directory listing, which is then stored and rendered in the Argo Server web interface. When another user views this listing, the injected script executes within their browser context under the Argo Server origin. This execution context allows the attacker to perform API actions with the victim’s privileges, potentially leading to unauthorized operations such as workflow manipulation, data exfiltration, or privilege escalation within the Kubernetes environment. The vulnerability affects Argo Workflows versions prior to 3.6.17 and versions from 3.7.0 up to but not including 3.7.8. The issue requires the attacker to have workflow author privileges and user interaction (the victim must view the malicious artifact listing). The CVSS 4.0 base score is 7.3 (high severity), reflecting network attack vector, high impact on confidentiality, integrity, and availability, but with high attack complexity and requiring user interaction. No known exploits in the wild have been reported as of the publication date. The vulnerability is mitigated by upgrading to versions 3.6.17 or 3.7.8 and later, which properly sanitize inputs to prevent script injection.

For European organizations leveraging Kubernetes and Argo Workflows for container orchestration, this vulnerability poses significant risks. Successful exploitation can lead to unauthorized execution of API actions with the victim’s privileges, potentially compromising workflow integrity, exposing sensitive operational data, or disrupting automated job orchestration. This could affect critical business processes relying on automated workflows, leading to operational downtime or data breaches. Given the widespread adoption of Kubernetes and cloud-native technologies in Europe, especially in sectors like finance, manufacturing, and public services, the impact could be substantial. Additionally, the ability to execute scripts in the context of the Argo Server origin may facilitate lateral movement within the cluster or pivoting to other systems. The requirement for workflow author privileges limits the attack surface but insider threats or compromised developer accounts increase risk. The need for user interaction (viewing the malicious artifact listing) means social engineering or phishing could be leveraged to trigger exploitation. Overall, the vulnerability threatens confidentiality, integrity, and availability of Kubernetes-based workflow environments in European enterprises.

1. Upgrade all Argo Workflows deployments to version 3.6.17 or 3.7.8 and later to ensure the vulnerability is patched. 2. Implement strict role-based access control (RBAC) to limit workflow author privileges only to trusted users, reducing the risk of malicious artifact injection. 3. Monitor and audit workflow artifact directories for suspicious or unexpected script content. 4. Educate users to be cautious when interacting with artifact listings, especially if sourced from untrusted workflow authors. 5. Employ network segmentation and zero-trust principles around Kubernetes management interfaces to limit exposure. 6. Integrate Web Application Firewall (WAF) rules to detect and block potential XSS payloads targeting the Argo Server interface. 7. Regularly review and update Kubernetes and Argo Workflows security configurations and keep dependencies up to date. 8. Consider implementing Content Security Policy (CSP) headers in the Argo Server to mitigate impact of any residual XSS vulnerabilities.