CVE-2023-4853: Quarkus Auth Bypass Vulnerability

CVE-2023-4853 Overview

A significant authorization bypass vulnerability has been discovered in Quarkus, the popular Kubernetes-native Java framework. The flaw exists in how HTTP security policies handle certain character permutations when processing incoming requests, leading to incorrect evaluation of permissions. This vulnerability allows attackers to craft specially formatted HTTP requests that bypass security policy enforcement, potentially gaining unauthorized access to protected endpoints and causing denial of service conditions.

Critical Impact

Attackers can bypass HTTP security policies entirely, gaining unauthorized access to protected API endpoints and potentially disrupting service availability through denial of service attacks.

Affected Products

• Quarkus (multiple versions)
• Red Hat Build of Quarkus
• Red Hat Build of OptaPlanner 8.0
• Red Hat Decision Manager 7.0
• Red Hat Integration Camel K
• Red Hat Integration Camel Quarkus
• Red Hat Integration Service Registry
• Red Hat JBoss Middleware
• Red Hat OpenShift Serverless
• Red Hat Process Automation Manager 7.0
• Red Hat OpenShift Container Platform 4.10, 4.11, 4.12
• Red Hat Enterprise Linux 8.0

Discovery Timeline

• September 20, 2023 - CVE-2023-4853 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-4853

Vulnerability Analysis

This vulnerability represents an authorization bypass flaw (CWE-863: Incorrect Authorization) combined with improper neutralization of input leaders (CWE-148). The core issue lies in Quarkus's HTTP security policy implementation, which fails to properly sanitize certain character sequences in incoming HTTP requests.

When Quarkus processes HTTP requests against defined security policies, the path matching and permission evaluation logic does not correctly handle specific character permutations. This improper input handling creates a gap between what the security policy intends to protect and what actually gets evaluated, allowing crafted requests to slip through authorization checks undetected.

The vulnerability is exploitable over the network without requiring authentication or user interaction, though successful exploitation requires specific conditions to be met. The impact affects confidentiality, integrity, and availability of the affected systems, as attackers can access protected resources, potentially modify data, and cause service disruptions.

Root Cause

The root cause stems from insufficient input sanitization in the HTTP security policy evaluation logic. The Quarkus framework's request routing and security enforcement components fail to normalize or properly validate certain character sequences before matching them against configured security policies. This inconsistency between how URLs are parsed for routing versus how they're evaluated against security policies creates the authorization bypass condition.

Attack Vector

The attack is network-based and can be executed remotely against any Quarkus application that relies on HTTP security policies for access control. An attacker can craft HTTP requests containing specific character permutations that the security policy engine fails to properly evaluate.

The attack flow typically involves:

1. Identifying a protected endpoint on a Quarkus application
2. Crafting an HTTP request with character sequences that bypass policy matching
3. Sending the request to access the protected endpoint without proper authorization
4. Potentially chaining multiple requests to achieve denial of service

Organizations using Quarkus-based applications with security policies defined for path-based access control are particularly at risk. The vulnerability affects microservices architectures where Quarkus is commonly deployed, including Red Hat OpenShift environments.

Detection Methods for CVE-2023-4853

Indicators of Compromise

• Unusual HTTP requests with non-standard character sequences targeting protected API endpoints
• Access log entries showing successful requests to endpoints that should require authentication
• Unexpected spikes in requests to sensitive administrative or internal endpoints
• Authentication bypass patterns in web application firewall (WAF) logs

Detection Strategies

• Implement web application firewall rules to detect and block requests containing suspicious character permutations in URL paths
• Configure application logging to capture detailed request information including raw URL paths for forensic analysis
• Deploy runtime application self-protection (RASP) solutions to monitor for authorization bypass attempts
• Use SentinelOne's application security capabilities to detect anomalous request patterns targeting Quarkus applications

Monitoring Recommendations

• Enable verbose access logging on Quarkus applications to capture full request details
• Monitor for access to protected endpoints without corresponding authentication events
• Set up alerts for unusual HTTP request patterns that deviate from normal application usage
• Correlate web server logs with application authorization events to identify potential bypass attempts

How to Mitigate CVE-2023-4853

Immediate Actions Required

• Update Quarkus to the latest patched version immediately
• Review HTTP security policy configurations and ensure they cover all intended protected paths
• Implement additional network-level access controls as defense-in-depth measures
• Audit access logs for signs of exploitation attempts prior to patching

Patch Information

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

• Red Hat Security Advisory RHSA-2023:5170
• Red Hat Security Advisory RHSA-2023:5310
• Red Hat Security Advisory RHSA-2023:5337
• Red Hat Security Advisory RHSA-2023:5446
• Red Hat Security Advisory RHSA-2023:5479
• Red Hat Security Advisory RHSA-2023:5480
• Red Hat Security Advisory RHSA-2023:6107
• Red Hat Security Advisory RHSA-2023:6112
• Red Hat Security Advisory RHSA-2023:7653

For detailed vulnerability information, refer to Red Hat's CVE-2023-4853 Security Bulletin.

Workarounds

• Deploy a reverse proxy or web application firewall in front of Quarkus applications to perform additional URL normalization and validation
• Implement IP-based access restrictions to limit exposure of sensitive endpoints while patches are being applied
• Add redundant authorization checks at the application code level for critical endpoints
• Consider temporarily disabling access to sensitive endpoints if patching cannot be performed immediately

# Example: Configure nginx as reverse proxy with URL normalization
server {
    listen 80;
    server_name your-quarkus-app.example.com;
    
    # Normalize URLs and reject suspicious patterns
    if ($request_uri ~* "[\\x00-\\x1f]") {
        return 400;
    }
    
    location / {
        proxy_pass http://localhost:8080;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
}