CVE-2022-31102 is a cross-site scripting (XSS) vulnerability identified in Argo CD, a popular declarative GitOps continuous delivery tool for Kubernetes environments. The vulnerability affects Argo CD versions starting from 2.3.0 up to but not including 2.3.6, and versions from 2.4.0 up to but not including 2.4.5. The flaw resides in the `/auth/callback` page, which is part of the single sign-on (SSO) authentication flow. Improper neutralization of input allows an attacker to inject arbitrary JavaScript code into this page. However, exploitation requires several preconditions: the attacker must have access to the API server's encryption key, a method to add a cookie to the victim's browser, and the ability to trick the victim into visiting a maliciously crafted `/auth/callback` URL. Because possession of the encryption key already grants significant control over the system, the XSS attack does not elevate privileges beyond what is possible with the key alone. The vulnerability is classified as medium severity due to these constraints. No known exploits are currently in the wild, and no workarounds exist. Patches addressing this vulnerability were released in Argo CD versions 2.3.6 and 2.4.5. The root cause is CWE-79, indicating improper input sanitization during web page generation, which is a common vector for XSS attacks. This vulnerability highlights the importance of robust input validation and secure handling of authentication callbacks in web applications, especially those managing critical infrastructure such as Kubernetes clusters.

For European organizations utilizing Argo CD with SSO enabled, this vulnerability could potentially allow attackers who have already compromised the API server's encryption key to perform XSS attacks that impersonate legitimate users. While the direct impact is limited by the prerequisite possession of the encryption key, successful exploitation could facilitate session hijacking, credential theft, or further social engineering attacks within the victim's browser context. This could lead to unauthorized access to Kubernetes deployment pipelines, manipulation of continuous delivery workflows, and potential disruption or compromise of production environments. Given the critical role of Argo CD in automating deployments, any compromise could affect the integrity and availability of applications and services. Additionally, the ability to impersonate users might aid attackers in evading detection or escalating privileges within the organization’s infrastructure. The lack of known exploits reduces immediate risk, but the presence of this vulnerability in widely used versions necessitates prompt remediation to prevent potential targeted attacks, especially in sectors with high compliance requirements such as finance, healthcare, and critical infrastructure in Europe.

European organizations should prioritize upgrading Argo CD instances to versions 2.3.6 or 2.4.5 or later to apply the official patches that remediate this vulnerability. Since no workaround exists, patching is the primary defense. Additionally, organizations should enforce strict access controls around the API server's encryption keys, including limiting key access to essential personnel and services, employing hardware security modules (HSMs) where possible, and rotating keys regularly to reduce exposure. Monitoring and logging of API server key usage and authentication flows should be enhanced to detect anomalous activities that could indicate attempts to exploit this vulnerability. Implementing Content Security Policy (CSP) headers in the Argo CD web interface can help mitigate the impact of potential XSS attacks by restricting the execution of unauthorized scripts. Organizations should also educate users about phishing risks related to malicious `/auth/callback` URLs to reduce the likelihood of successful social engineering. Finally, conducting regular security assessments and penetration tests focusing on the SSO implementation and web interface input validation can help identify and remediate similar issues proactively.