CVE-2024-7885: Undertow Information Disclosure Vulnerability

CVE-2024-7885 Overview

A race condition vulnerability exists in Undertow's ProxyProtocolReadListener component where the same StringBuilder instance is reused across multiple requests on the same HTTP connection. When the parseProxyProtocolV1 method processes concurrent requests, this shared state can lead to information leakage between different requests or responses. The vulnerability primarily manifests as errors and connection termination but poses a significant risk of unintended data exposure in multi-request environments where sensitive information from one request may erroneously appear in another.

Critical Impact

Information leakage between HTTP requests in multi-tenant environments using Undertow with Proxy Protocol v1, potentially exposing sensitive data from one request to unrelated clients.

Affected Products

• Red Hat Build of Apache Camel - Hawtio
• Red Hat Build of Apache Camel for Spring Boot
• Red Hat Build of Keycloak
• Red Hat Data Grid 8.0.0
• Red Hat Integration Camel K
• Red Hat JBoss Enterprise Application Platform 7.0.0 and 8.0.0
• Red Hat JBoss Fuse 7.0.0
• Red Hat Process Automation 7.0
• Red Hat Single Sign-On 7.0

Discovery Timeline

• August 21, 2024 - CVE-2024-7885 published to NVD
• January 19, 2026 - Last updated in NVD database

Technical Details for CVE-2024-7885

Vulnerability Analysis

This vulnerability is classified as a Race Condition (CWE-362) affecting Undertow's proxy protocol handling implementation. The core issue lies in the ProxyProtocolReadListener class, which improperly reuses a StringBuilder instance across multiple HTTP requests sharing the same connection. In high-concurrency scenarios where multiple requests traverse the same persistent connection, the shared mutable state can cause data from one request to leak into another.

The vulnerability is exploitable over the network without requiring authentication or user interaction, making it accessible to remote attackers. While the primary observable impact is connection termination and application errors, the underlying race condition creates an opportunity for cross-request information disclosure. This is particularly concerning in multi-tenant deployments where different users' requests may traverse the same connection pool.

Root Cause

The root cause stems from improper thread-safety practices in the parseProxyProtocolV1 method within ProxyProtocolReadListener. Instead of creating a new StringBuilder instance for each request or properly synchronizing access, the code reuses the same instance. When multiple threads process requests on a shared connection, the StringBuilder content from one request can persist and contaminate subsequent requests before being cleared or reset.

Attack Vector

The attack vector is network-based and can be exploited by an attacker who can send multiple concurrent HTTP requests through a system using Undertow with Proxy Protocol v1 enabled. In load-balanced or reverse-proxy configurations—common in enterprise deployments—an attacker could:

1. Establish persistent HTTP connections to the target server
2. Send rapid, concurrent requests over these connections
3. Observe responses for data leakage from other users' requests
4. Exploit any sensitive information inadvertently exposed

The vulnerability is particularly impactful in shared hosting environments, multi-tenant SaaS applications, and identity management systems like Keycloak where request isolation is critical for security.

Detection Methods for CVE-2024-7885

Indicators of Compromise

• Unexpected connection reset errors in Undertow application logs, particularly in ProxyProtocolReadListener stack traces
• Intermittent HTTP 500 errors correlating with high-concurrency periods
• User reports of receiving data belonging to other users or sessions
• Log entries showing mismatched proxy protocol headers or malformed request data

Detection Strategies

• Monitor application logs for ProxyProtocolReadListener exceptions or StringBuilder-related errors during HTTP request processing
• Implement request correlation logging to detect cases where response data doesn't match request context
• Deploy network intrusion detection rules to identify unusual patterns of rapid connection reuse
• Enable Undertow debug logging temporarily during maintenance windows to analyze proxy protocol parsing behavior

Monitoring Recommendations

• Configure alerting on Undertow connection error rates exceeding baseline thresholds
• Implement distributed tracing to correlate requests across load-balanced instances and detect data mixing
• Monitor for unusual spikes in HTTP persistent connection activity
• Review application access logs for evidence of cross-user data exposure

How to Mitigate CVE-2024-7885

Immediate Actions Required

• Update affected Red Hat products to patched versions as specified in the Red Hat Security Advisories
• If immediate patching is not possible, consider disabling Proxy Protocol v1 support temporarily
• Review application architecture to identify all systems using Undertow-based products
• Assess exposure in multi-tenant environments and prioritize patching accordingly

Patch Information

Red Hat has released multiple security advisories addressing this vulnerability. Organizations should apply the appropriate patches based on their deployed products:

• Red Hat Security Advisory RHSA-2024:6508
• Red Hat Security Advisory RHSA-2024:6883
• Red Hat Security Advisory RHSA-2024:7441
• Red Hat Security Advisory RHSA-2024:7442
• Red Hat Security Advisory RHSA-2024:7735
• Red Hat Security Advisory RHSA-2024:7736
• Red Hat Security Advisory RHSA-2024:8080
• Red Hat Security Advisory RHSA-2024:11023

Additional details are available at the Red Hat CVE-2024-7885 Details page and Red Hat Bugzilla Report #2305290.

Workarounds

• Disable Proxy Protocol v1 support in Undertow configuration if the feature is not required for your deployment
• Implement network segmentation to limit exposure of vulnerable services to trusted networks only
• Configure connection pooling limits to reduce the likelihood of connection reuse across different user contexts
• Deploy a web application firewall (WAF) with rate limiting to reduce concurrent request throughput

# Example: Disable Proxy Protocol in standalone.xml for JBoss EAP
# Locate the http-listener configuration and remove or comment out proxy-protocol attribute
# Before: <http-listener name="default" socket-binding="http" proxy-protocol="true"/>
# After:  <http-listener name="default" socket-binding="http"/>