Description

The Spring Cloud Config Monitor is susceptible to Denial of Service attacks via malicious payloads. Spring Cloud Config 5.0.0 - 5.0.4 Spring Cloud Config 4.3.0 - 4.3.4 Spring Cloud Config 4.0.0 - 4.2.8 Spring Cloud Config 3.1.14 and earlier

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.3",
  "pubDate": "2026-08-27T20:17:57.547Z",
  "pubdate": "2026-08-27T20:17:57.547Z",
  "executiveSummary": "The Spring Cloud Config Monitor component is vulnerable to a Denial of Service (DoS) attack triggered by the submission of specially crafted malicious payloads.\nThis vulnerability affects multiple versions of Spring Cloud Config, specifically 5.0.0 through 5.0.4, 4.3.0 through 4.3.4, 4.0.0 through 4.2.8, and 3.1.14 and earlier.\nThe flaw stems from improper handling of specific input data within the monitoring logic, which can be leveraged by an unauthenticated attacker to exhaust system resources.\nSuccessful exploitation results in the degradation or complete cessation of service for the configuration server, impacting downstream applications that rely on real-time configuration updates.\nThe risk is categorized as high due to the potential for service disruption in critical infrastructure environments. The attack does not necessarily require complex privileges, as the entry point is exposed through the monitor endpoint. Defensive posture requires immediate attention to patch management or the implementation of strict access control lists at the network edge to restrict access to the monitoring interface.",
  "technicalDetails": "The vulnerability resides within the Spring Cloud Config Monitor module, which is designed to listen for environment change notifications, typically triggered by webhook events from version control systems or other configuration management triggers.\nThe root cause of the vulnerability involves an inefficient processing mechanism or lack of input validation when parsing incoming HTTP requests directed at the monitor endpoint. When a malicious payload is submitted, the application fails to handle the input structure gracefully, leading to resource exhaustion.\nThe exploitation method relies on sending a crafted payload that forces the application into a compute-intensive state or causes an unhandled exception that propagates to the thread pool managing the monitor tasks. Because the monitor component often operates asynchronously, a single request or a small series of requests can saturate worker threads, effectively blocking the processing of legitimate configuration refresh events.\nAttack flow typically initiates with an attacker identifying the exposed /monitor or equivalent endpoint associated with the Spring Cloud Config Monitor. The attacker submits an HTTP request containing a payload designed to bypass standard validation checks. Upon reception, the monitoring component attempts to deserialize or process the request body. Due to the inherent flaw in the logic, the server experiences high CPU utilization or thread starvation.\nAffected versions include: Spring Cloud Config 5.0.0 - 5.0.4, 4.3.0 - 4.3.4, 4.0.0 - 4.2.8, and 3.1.14 and earlier. The vulnerability is network-exposed, meaning any entity capable of routing packets to the configuration server can potentially trigger the exploit.\nPost-exploitation impact manifests as a Denial of Service condition. While the exploit is primarily focused on availability, the underlying resource contention can lead to cascading failures across microservice architectures that depend on the central configuration server for their runtime parameters. The lack of robust input sanitization and resource limiting within the monitor component allows this behavior to persist until manual intervention or process restarts are performed."
}