CVE-2025-59537 is a high-severity vulnerability affecting multiple versions of Argo CD, a popular declarative GitOps continuous delivery tool for Kubernetes. The vulnerability arises from improper input validation (CWE-20) and null pointer dereference (CWE-476) in the /api/webhook endpoint of the argocd-server process. Specifically, when Argo CD is configured with default settings and no webhook.gogs.secret is set, the API server fails to properly validate incoming JSON payloads from Gogs push events. If the commits[].repo field in the JSON payload is missing or null, the argocd-server process crashes, resulting in a denial of service (DoS) condition for legitimate clients. This vulnerability affects versions 1.2.0 through 1.8.7, 2.0.0-rc1 through 2.14.19, 3.0.0-rc1 through 3.2.0-rc1, as well as specific patch versions 3.1.7 and 3.0.18. The issue has been addressed in versions 2.14.20, 3.2.0-rc2, 3.1.8, and 3.0.19. The CVSS v3.1 base score is 7.5, reflecting a high severity due to the vulnerability's ability to cause complete service disruption without requiring authentication or user interaction. The attack vector is network-based (AV:N), with low attack complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The impact is limited to availability (A:H), with no confidentiality or integrity impact. No known exploits are currently reported in the wild. This vulnerability could be exploited by sending a crafted Gogs webhook push event with a malformed JSON payload to the vulnerable Argo CD API endpoint, causing the server process to crash and deny service to users relying on Argo CD for Kubernetes continuous delivery workflows.

For European organizations, the impact of CVE-2025-59537 can be significant, especially for those relying on Argo CD for Kubernetes deployment automation and GitOps workflows. A successful exploitation results in denial of service, disrupting continuous delivery pipelines and potentially delaying critical application updates or infrastructure changes. This disruption can affect development velocity, operational stability, and incident response capabilities. Organizations in sectors with stringent uptime requirements, such as finance, healthcare, telecommunications, and public services, may experience operational and reputational damage. Additionally, since the vulnerability does not require authentication or user interaction, it can be exploited remotely by unauthenticated attackers, increasing the risk of widespread disruption. Although no direct confidentiality or integrity impact is present, the availability impact alone can lead to cascading effects in complex Kubernetes environments, including delayed security patches or configuration changes, which could indirectly increase exposure to other threats.

European organizations should prioritize upgrading Argo CD to the fixed versions: 2.14.20, 3.2.0-rc2, 3.1.8, or 3.0.19, depending on their current deployment version. Until upgrades are applied, organizations should implement strict network-level controls to restrict access to the /api/webhook endpoint, limiting it only to trusted sources such as verified Gogs webhook servers. Configuring webhook.gogs.secret is critical to ensure that only authenticated webhook events are processed, preventing unauthenticated or malformed requests from triggering the vulnerability. Monitoring and alerting on argocd-server process crashes or abnormal webhook traffic patterns can provide early detection of exploitation attempts. Additionally, implementing Web Application Firewalls (WAFs) or API gateways with payload validation can help filter out malformed JSON payloads targeting the commits[].repo field. Regular security audits of Kubernetes continuous delivery tools and integration of vulnerability scanning into CI/CD pipelines will help identify and remediate similar issues proactively.