CVE-2023-41337 : Vulnerability Insights and Analysis

A security vulnerability has been identified in h2o HTTP server versions up to 2.3.0-beta2 that could allow a malicious entity to misdirect HTTPS requests under specific configurations. This article details the impact, technical aspects, and mitigation steps for CVE-2023-41337.

Understanding CVE-2023-41337

This section explores the details of the CVE-2023-41337 vulnerability affecting h2o HTTP server.

What is CVE-2023-41337?

h2o, an HTTP server supporting HTTP/1.x, HTTP/2, and HTTP/3, is susceptible to misdirection of HTTPS requests in versions up to 2.3.0-beta2. Attackers can redirect TLS connections to unintended backend servers, potentially exposing sensitive information.

The Impact of CVE-2023-41337

The vulnerability allows attackers to intercept and observe HTTPS requests meant for legitimate servers. By misdirecting TLS sessions, sensitive data can be exposed to unauthorized entities.

Technical Details of CVE-2023-41337

This section delves into the technical aspects of the CVE-2023-41337 vulnerability.

Vulnerability Description

Attackers can exploit h2o's configuration settings to redirect TLS connections, leading to the interception of HTTPS requests and potential data exposure.

Affected Systems and Versions

The vulnerability affects h2o HTTP server versions up to 2.3.0-beta2 that are configured to listen to multiple addresses or ports with different backend servers.

Exploitation Mechanism

The attack involves redirecting TLS connection packets to a different address or port than intended, allowing malicious entities to intercept and potentially manipulate HTTPS requests.

Mitigation and Prevention

This section outlines steps to mitigate and prevent exploitation of CVE-2023-41337.

Immediate Steps to Take

Users should apply the provided patch available at commit 35760540337a47e5150da0f4a66a609fad2ef0ab to address the vulnerability. Alternatively, consider using global-level listen directives instead of host-level ones.

Long-Term Security Practices

To enhance security posture, regularly update h2o HTTP server software and apply patches promptly to prevent exploitation of known vulnerabilities.

Patching and Updates

Stay informed about security advisories and updates from h2o. Implement a robust patch management process to ensure timely deployment of security fixes.