External risk intelligence

Spring Cloud Config Missing Authentication Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-47837

Spring Cloud Config Server is typically deployed as a backend infrastructure component to manage application configurations. While it may be exposed to the network to serve multiple microservices, it is not designed to be a public-facing internet service, though it can be reachable in some network architectures.

Missing Authentication

Vmware Spring Cloud Config

before 3.1.154.0.0 to before 4.2.94.3.0 to before 4.3.55.0.0 to before 5.0.5

Halo Surface Signal: 3 out of 5 — possibly public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This vulnerability involves a critical function in Spring Cloud Config that does not properly validate webhook requests. This could potentially allow unauthorized access and manipulation of configuration data if exploited. The main concern at this time is confirming if this technology is in use and if it is exposed to potential threats.

Unvalidated requests to a configuration server.
Affects centralized application configuration management.
Confirm relevance and assess exposure of the technology.

Attack Path

How an attacker could exploit the issue

An attacker could target the Spring Cloud Config Server over the network and send unauthenticated webhook requests to its `/monitor` endpoint. Because these requests are not validated, this could allow an attacker to trigger actions on the server, potentially leading to a complete compromise.

No authentication required for access.
Triggered by sending requests to `/monitor`.
Risk of complete system compromise.

Live Threat

Current exploitation, exposure, and threat context

Unvalidated webhook requests to Spring Cloud Config Server's `/monitor` endpoint could allow an unauthenticated attacker to trigger unexpected service behavior or gain access to sensitive information. This could occur when the server is reachable over the network and configured to process such requests without proper authentication.

Sensitive configuration data could be exposed.
Unauthenticated requests may bypass security checks.
Service disruption or unauthorized access may occur.

Operational Fix

Recommended remediation, mitigation, and detection steps

Teams managing the application runtime or core infrastructure, potentially including platform or cloud teams, should address this vulnerability. The first practical step is to identify all instances of Spring Cloud Config Server, determine their network exposure, and assess business criticality to prioritize remediation efforts by locating the accountable owner.

Platform or application teams own the issue.
Verify network reachability and business criticality.
Coordinate remediation with vendor and asset owners.

Supplementary metadata

CVSS vector

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Frequently asked questions

What is Spring Cloud Config?

Spring Cloud Config is a server-side tool used in software development to provide centralized, externalized configuration for distributed systems. It allows applications to manage their environment-specific settings—such as database URLs or feature flags—in one place rather than hardcoding them. It is widely used in microservice architectures to keep settings consistent across multiple running services.

What does CWE-306 mean for CVE-2026-47837?

CWE-306, or Missing Authentication for Critical Function, means that a sensitive part of the software does not verify the identity of the person or system making a request. In the context of CVE-2026-47837, the Spring Cloud Config Server's /monitor endpoint lacks these identity checks, allowing anyone who can reach the endpoint to execute commands that should be protected.

How is this vulnerability triggered?

The vulnerability is triggered when an attacker sends an unauthenticated network request directly to the /monitor endpoint of a vulnerable Spring Cloud Config Server. If the request is not authenticated, the server processes it automatically. Note that simply viewing the server interface is not the trigger; the issue specifically relates to the lack of validation on incoming webhook-style requests sent to that specific management endpoint.

Do I need to worry if my server is internal?

Halo Surface Signal indicates that while Spring Cloud Config is typically a backend component, it is often reachable across network segments to support various microservices. Even if your server is not on the public internet, internal reachability can still pose a risk if unauthorized users or compromised services within your network can send requests to the server's /monitor endpoint.

When should I prioritize fixing this?

You should prioritize this by first performing an inventory to locate all instances of Spring Cloud Config within your environment. Once identified, assess which servers are reachable over your network and determine their business criticality. Coordinate with your platform or application infrastructure teams to confirm the version in use and plan for necessary updates to a patched release.

References

spring.io/security/cve-2026-47837

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.