CVE-2025-11965: Eclipse Vert.x Auth Bypass Vulnerability

CVE-2025-11965 Overview

CVE-2025-11965 is a path traversal and access control bypass vulnerability in Eclipse Vert.x, a popular reactive toolkit for building applications on the JVM. The vulnerability exists in the StaticHandler component, where configuration designed to restrict access to hidden files fails to properly restrict access to hidden directories. This allows unauthorized users to retrieve sensitive files within hidden directories, such as .git/config, potentially exposing credentials, repository configurations, and other sensitive information.

Critical Impact

Unauthorized access to hidden directories can expose sensitive configuration files, credentials, and source code repository information to attackers, potentially leading to further compromise of development infrastructure and deployed applications.

Affected Products

• Eclipse Vert.x versions 4.0.0 through 4.5.21
• Eclipse Vert.x versions 5.0.0 through 5.0.4

Discovery Timeline

• 2025-10-22 - CVE CVE-2025-11965 published to NVD
• 2026-01-16 - Last updated in NVD database

Technical Details for CVE-2025-11965

Vulnerability Analysis

This vulnerability is classified under CWE-552 (Files or Directories Accessible to External Parties), which describes a condition where files or directories are accessible to unauthorized actors. The flaw resides in the StaticHandler component of Eclipse Vert.x, which is commonly used to serve static content in web applications built with the framework.

When developers configure the StaticHandler to block access to hidden files (files starting with a dot, such as .htaccess or .env), the implementation only enforces this restriction at the file level. Hidden directories, which also begin with a dot character, are not subject to the same access controls. This inconsistency allows attackers to craft requests that access files within hidden directories, even when hidden file access is explicitly disabled.

The vulnerability is exploitable over the network without requiring authentication or user interaction. The impact includes potential exposure of confidential configuration data and the ability to modify application behavior if write operations are also exposed.

Root Cause

The root cause of this vulnerability is an incomplete implementation of access control logic in the StaticHandler component. The code responsible for checking whether a requested resource is hidden only evaluates the final file component of the path, rather than checking all path segments for hidden directory indicators. This means that while a request for /.env would be blocked, a request for /.git/config would be permitted because config is not a hidden file, even though it resides within the hidden .git directory.

Attack Vector

The attack vector is network-based and can be exploited remotely by any unauthenticated user who can send HTTP requests to a vulnerable Vert.x application. An attacker would craft HTTP requests targeting hidden directories that commonly contain sensitive information.

Common targets for exploitation include:

• .git/config - Contains repository configuration, potentially including remote URLs with credentials
• .git/HEAD - Reveals the current branch reference
• .svn/entries - Subversion repository metadata
• .env files within hidden directories - Environment configuration with secrets

The exploitation is straightforward: an attacker simply needs to enumerate common hidden directory paths and request files within them. No special tools or complex exploitation chains are required.

Detection Methods for CVE-2025-11965

Indicators of Compromise

• HTTP requests containing paths with hidden directory patterns (e.g., /.git/, /.svn/, /.hg/)
• Unusual access patterns targeting configuration files within hidden directories
• Successful HTTP responses (200 OK) for requests to hidden directory contents
• Log entries showing access to files like .git/config, .git/HEAD, or .gitignore

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block requests containing hidden directory path patterns
• Configure log analysis to alert on requests matching regex patterns like /\.[a-zA-Z]+/ in URL paths
• Monitor for reconnaissance activity involving sequential requests to common hidden directory paths
• Deploy intrusion detection signatures for known hidden directory enumeration tools

Monitoring Recommendations

• Enable detailed access logging for all static content requests in Vert.x applications
• Set up alerts for HTTP 200 responses to requests containing hidden directory paths
• Review web server logs regularly for attempts to access .git, .svn, .hg, or similar directories
• Implement file integrity monitoring on sensitive configuration files that may have been exposed

How to Mitigate CVE-2025-11965

Immediate Actions Required

• Upgrade Eclipse Vert.x to version 4.5.22 or later for the 4.x branch, or version 5.0.5 or later for the 5.x branch
• Audit application configurations to identify any StaticHandler instances serving directories that may contain hidden subdirectories
• Review web server access logs for evidence of exploitation attempts or successful unauthorized access
• Rotate any credentials that may have been exposed in hidden directory files such as .git/config

Patch Information

Eclipse has released patched versions that properly enforce hidden file restrictions on hidden directories as well. Organizations should upgrade to Eclipse Vert.x 4.5.22 or later for the 4.x series, or 5.0.5 or later for the 5.x series. The security advisory with additional details is available at the Eclipse GitLab Vulnerability Report.

Workarounds

• Configure web server or reverse proxy rules to explicitly block access to hidden directories at the infrastructure level
• Remove hidden directories (such as .git) from web-accessible static content directories during deployment
• Implement additional access control middleware that validates path segments before serving static content
• Use a dedicated CDN or object storage service for static content that does not include hidden directories

# Example nginx configuration to block hidden directories
location ~ /\. {
    deny all;
    return 404;
}