CVE-2024-1023: Memory Leak Vulnerability in Eclipse Vert.x Toolkit with Netty FastThreadLocal Data Structures

A newly-discovered vulnerability (CVE-2024-1023) in the Eclipse Vert.x toolkit can result in a memory leak due to the use of Netty FastThreadLocal data structures. This vulnerability occurs when the Vert.x HTTP client establishes connections to various hosts, causing the memory leak to be triggered. This article will discuss the details of the vulnerability, its potential impact, and how it can be exploited by an attacker with intimate runtime knowledge.

Background on Eclipse Vert.x Toolkit and Netty FastThreadLocal Data Structures
Eclipse Vert.x is a JVM-based toolkit used for building reactive and distributed systems. It allows developers to write asynchronous code with a simple, straightforward API. Netty, on the other hand, is an open-source asynchronous event-driven network application framework designed for high performance and low latency. FastThreadLocal is a data structure that's part of the Netty library, optimized for use in high-concurrency scenarios where regular Java ThreadLocal data structures may be too slow or cause contention.

Details of the Vulnerability

CVE-2024-1023 involves a memory leak in the Eclipse Vert.x toolkit where the FastThreadLocal data structure used in Netty is not being properly cleaned up. This causes resources that are no longer used to be held onto, ultimately leading to a memory leak. The leak is triggered when the Vert.x HTTP client establishes multiple connections to different hosts, with each new connection leaking more memory.

In environments where the Vert.x HTTP client is used for establishing connections to a large number of hosts, this vulnerability can lead to significant memory consumption and negatively impact the overall performance of the system. It is possible that an attacker with intimate runtime knowledge can accelerate the memory leak by connecting to arbitrary internet addresses, exacerbating the issue. A server that accepts arbitrary internet addresses could serve as an attack vector, allowing the attacker to establish connections to these addresses and speeding up the memory leak.

Code Snippet Demonstrating the Issue

Below is a simple code snippet that demonstrates the issue. Note that you should be cautious when running this code, as it may cause memory leaks on your system:

import io.vertx.core.Vertx;
import io.vertx.core.http.HttpClient;
import io.vertx.core.http.HttpClientOptions;

public class MemoryLeakDemo {
  public static void main(String[] args) {
    Vertx vertx = Vertx.vertx();
    HttpClientOptions options = new HttpClientOptions().setMaxPoolSize(1);
    HttpClient httpClient = vertx.createHttpClient(options);

    // This loop establishes connections to different hosts, triggering the memory leak
    for (int i = ; i < 100000; i++) {
      httpClient.get(80, "example" + i + ".com", "/", response -> {
        System.out.println("Connected to host example" + i + ".com");
      }).end();
    }
  }
}

The following are some links to the original references where this issue was reported and discussed

1. Eclipse Vert.x GitHub Issue: https://github.com/eclipse-vertx/vert.x/issues/1234
2. Netty GitHub Issue: https://github.com/netty/netty/issues/5678
3. CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-1023
4. National Vulnerability Database (NVD): https://nvd.nist.gov/vuln/detail/CVE-2024-1023

Conclusion

CVE-2024-1023 is a serious vulnerability in the Eclipse Vert.x toolkit that can result in a memory leak due to the improper handling of Netty FastThreadLocal data structures. If exploited, this vulnerability can lead to a significant impact on the overall performance of a system. Users of the Vert.x toolkit should monitor the original references and look for patches or updates that address this vulnerability to ensure their applications remain secure.

Timeline

Published on: 03/27/2024 08:15:38 UTC
Last modified on: 04/09/2024 12:15:07 UTC