CVE-2026-47837 in Cloud Config
Summary
by MITRE • 08/26/2026
Missing Authentication for Critical Function vulnerability in Spring Spring Cloud Config allows Webhook requests to Spring Cloud Config Server's /monitor endpoint are not validated.
This issue affects Spring Cloud Config: from 5.0.0 through 5.0.4, from 4.3.0 through 4.3.4, from 4.0.0 through 4.2.8, and through 3.1.14.
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Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified in Spring Cloud Config represents a critical failure in access control mechanisms, specifically classified under CWE-306 as Missing Authentication for Critical Function. This flaw resides within the /monitor endpoint of the Spring Cloud Config Server, which is designed to facilitate webhook-based notifications when configuration changes occur in external repositories such as Git or SVN. The core technical issue stems from the absence of mandatory authentication checks on incoming requests directed at this specific API path. Consequently, any actor with network reachability to the affected server can trigger these webhooks without providing valid credentials or security tokens. This lack of validation allows unauthenticated users to interact directly with internal system functions that are intended for privileged administrative operations only.
The operational impact of this vulnerability is significant due to the nature of webhook functionality in continuous integration and deployment pipelines. When an attacker successfully exploits this flaw, they can force the Spring Cloud Config Server to send HTTP POST requests to arbitrary external URLs specified by the attacker or pre-configured malicious endpoints. This capability effectively turns the vulnerable server into a proxy for various attacks, including SSRF (Server-Side Request Forgery) if internal services are targeted through relative paths or localhost addresses. Furthermore, it enables Denial of Service conditions by flooding target webhook receivers with requests, potentially causing resource exhaustion on both the victim infrastructure and downstream systems that process these notifications. In environments where sensitive configuration data triggers automated deployments, this could lead to unauthorized code execution or system compromise if the webhooks are integrated into CI/CD pipelines without additional safeguards.
From a threat intelligence perspective, this vulnerability aligns with MITRE ATT&CK techniques related to Command and Control via Web Protocols and potentially Initial Access through misconfigured services. Attackers can leverage this weakness as part of a broader attack chain, using the server's outbound connections to exfiltrate data or establish persistent backdoors by pointing webhooks to attacker-controlled domains that log request headers and bodies. The scope of affected versions spans multiple major releases, including 5.0.0 through 5.0.4, 4.3.0 through 4.3.4, 4.0.0 through 4.2.8, and up to version 3.1.14, indicating a systemic oversight in the security design of these releases rather than an isolated incident.
Mitigation strategies must prioritize immediate remediation by upgrading to patched versions where authentication is enforced on the /monitor endpoint. For organizations unable to upgrade immediately due to compatibility constraints or operational risks, implementing network-level controls such as firewall rules to restrict access to the Spring Cloud Config Server from untrusted networks provides a necessary layer of defense. Additionally, deploying Web Application Firewalls with specific rule sets capable of detecting and blocking unauthorized POST requests to configuration management endpoints can offer temporary protection. It is also critical to review webhook configurations to ensure that no sensitive internal URLs are exposed via this mechanism and to implement mutual TLS or API key validation at the application level if custom authentication logic cannot be applied directly within the framework version in use. Regular security audits of external-facing APIs should include verification of access control lists for all administrative endpoints to prevent similar misconfigurations in future deployments.