CVE-2024-23639 in micronaut-core
Summary
by MITRE • 02/09/2024
Micronaut Framework is a modern, JVM-based, full stack Java framework designed for building modular, easily testable JVM applications with support for Java, Kotlin and the Groovy language. Enabled but unsecured management endpoints are susceptible to drive-by localhost attacks. While not typical of a production application, these attacks may have more impact on a development environment where such endpoints may be flipped on without much thought. A malicious/compromised website can make HTTP requests to `localhost`. Normally, such requests would trigger a CORS preflight check which would prevent the request; however, some requests are "simple" and do not require a preflight check. These endpoints, if enabled and not secured, are vulnerable to being triggered. Production environments typically disable unused endpoints and secure/restrict access to needed endpoints. A more likely victim is the developer in their local development host, who has enabled endpoints without security for the sake of easing development. This issue has been addressed in version 3.8.3. Users are advised to upgrade.
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Analysis
by VulDB Data Team • 03/02/2024
The vulnerability described in CVE-2024-23639 affects the Micronaut Framework, a modern JVM-based full stack framework that supports Java, Kotlin, and Groovy development. This security flaw specifically targets management endpoints that are enabled but not properly secured, creating a significant risk in development environments where such endpoints are commonly left accessible without adequate protection. The issue stems from the framework's handling of localhost requests and the inherent browser security mechanisms that govern cross-origin resource sharing. While production applications typically disable unused endpoints and implement proper access controls, development environments often lack these security measures, making them particularly vulnerable to exploitation.
The technical flaw revolves around the browser's CORS (Cross-Origin Resource Sharing) preflight mechanism and how it interacts with simple HTTP requests. When a malicious website attempts to make HTTP requests to localhost, normally the browser would enforce CORS preflight checks that prevent such cross-origin requests from succeeding. However, certain HTTP requests are classified as "simple" requests that bypass this preflight mechanism entirely. These simple requests can exploit the unsecured management endpoints that are enabled on localhost, allowing attackers to execute unauthorized operations against the framework. This vulnerability is particularly dangerous because it leverages the trust relationship that exists between browser and localhost, where browsers treat localhost requests as potentially more privileged than external requests.
The operational impact of this vulnerability is most pronounced in development environments where developers enable management endpoints for debugging and monitoring purposes without implementing proper security controls. Attackers can craft malicious websites that, when visited by a developer, automatically make HTTP requests to the locally running Micronaut application. These requests can potentially trigger administrative functions, access sensitive data, or even execute arbitrary code depending on the exposed endpoints and their implementation. The risk is significantly higher in development contexts because developers often prioritize convenience over security, leaving endpoints accessible without authentication mechanisms or access restrictions that would normally be present in production systems.
Security professionals should note that this vulnerability aligns with CWE-352 (Cross-Site Request Forgery) and relates to ATT&CK technique T1213 (Data from Information Repositories) and T1071.004 (Application Layer Protocol: DNS). The vulnerability represents a classic example of insufficient security controls in development environments and demonstrates how seemingly benign features can become security risks when not properly secured. Organizations should implement the remediation by upgrading to Micronaut Framework version 3.8.3 or later, which includes fixes for this specific vulnerability. Additionally, development teams should establish security practices that automatically disable unused endpoints, implement proper authentication for management interfaces, and conduct regular security assessments of development environments to prevent similar issues from arising in the future.