CVE-2024-20921: Oracle GraalVM Auth Bypass Vulnerability

CVE-2024-20921 Overview

CVE-2024-20921 is an information disclosure vulnerability in the Hotspot component of Oracle Java SE, Oracle GraalVM for JDK, and Oracle GraalVM Enterprise Edition. This vulnerability stems from incorrect default permissions (CWE-276) within the Hotspot JIT compiler, which can allow an unauthenticated attacker with network access to gain unauthorized access to critical data or complete access to all accessible data within the affected Java environments.

The vulnerability is particularly concerning because it can be exploited through APIs in the Hotspot component, including via web services that supply data to these APIs. Additionally, this vulnerability affects Java deployments in client environments running sandboxed Java Web Start applications or sandboxed Java applets that load and run untrusted code from the internet and rely on the Java sandbox for security.

Critical Impact

Successful exploitation allows unauthorized access to critical data or complete access to all Oracle Java SE, Oracle GraalVM for JDK, and Oracle GraalVM Enterprise Edition accessible data, potentially compromising sensitive information in enterprise Java environments.

Affected Products

• Oracle JDK: 8u391, 8u391-perf, 11.0.21, 17.0.9, 21.0.1
• Oracle JRE: 8u391, 8u391-perf, 11.0.21, 17.0.9, 21.0.1
• Oracle GraalVM for JDK: 17.0.9, 21.0.1
• Oracle GraalVM Enterprise Edition: 20.3.12, 21.3.8, 22.3.4

Discovery Timeline

• 2024-02-17 - CVE-2024-20921 published to NVD
• 2025-11-04 - Last updated in NVD database

Technical Details for CVE-2024-20921

Vulnerability Analysis

This vulnerability exists within the Hotspot component, which is responsible for just-in-time (JIT) compilation and runtime execution in Java Virtual Machines. The flaw relates to incorrect default permissions (CWE-276) that can be leveraged by an attacker to bypass intended security restrictions.

The Hotspot component is critical to Java's execution model, handling bytecode compilation to native machine code, garbage collection, and memory management. A security weakness in this component can have far-reaching implications for applications running on affected Java runtimes.

While the vulnerability requires high attack complexity to exploit successfully, no privileges or user interaction are required once network access is established. This makes the vulnerability accessible to remote attackers who can reach vulnerable Java services over the network.

Root Cause

The root cause of CVE-2024-20921 is improper default permissions (CWE-276) within the Hotspot component. This permission misconfiguration allows attackers to access data that should be protected by the Java security model. The vulnerability affects how the Hotspot JIT compiler handles certain operations, potentially exposing confidential information to unauthorized parties.

Attack Vector

The attack vector for this vulnerability is network-based and can be exploited through multiple protocols. Attackers can leverage this vulnerability in two primary scenarios:

1. Server-side exploitation: Through web services or APIs that interact with the vulnerable Hotspot component, attackers can craft malicious requests designed to trigger the vulnerability and exfiltrate sensitive data.

2. Client-side exploitation: In environments where sandboxed Java applets or Java Web Start applications are used, attackers can deliver malicious code (e.g., from the internet) that exploits the vulnerability to escape sandbox restrictions and access protected data.

The vulnerability does not require authentication or user interaction, but the high attack complexity indicates that successful exploitation requires specific conditions or advanced techniques.

Detection Methods for CVE-2024-20921

Indicators of Compromise

• Unusual data access patterns from Java processes accessing sensitive files or memory regions outside their normal scope
• Unexpected network traffic from Java applications to unknown external destinations
• Java process behavior anomalies including unusual CPU usage patterns during JIT compilation phases
• Log entries indicating unauthorized API calls or data access attempts within Java-based applications

Detection Strategies

• Implement runtime application self-protection (RASP) solutions to monitor Java application behavior for anomalous data access patterns
• Deploy network monitoring to detect unusual outbound traffic from Java-based services
• Configure Java logging to capture detailed information about API calls and data access operations
• Utilize SentinelOne's behavioral AI to detect exploitation attempts targeting the Hotspot component

Monitoring Recommendations

• Monitor Java process memory access patterns for signs of information disclosure attempts
• Implement centralized logging for all Java-based applications and services
• Deploy application-level monitoring to track API usage and data access in Java environments
• Regularly review security logs for evidence of reconnaissance or exploitation attempts

How to Mitigate CVE-2024-20921

Immediate Actions Required

• Inventory all systems running affected versions of Oracle Java SE, GraalVM for JDK, and GraalVM Enterprise Edition
• Prioritize patching for internet-facing Java applications and services
• Review and restrict network access to Java-based services where possible
• Consider temporarily disabling Java applets and Java Web Start if not business-critical

Patch Information

Oracle has addressed this vulnerability in the January 2024 Critical Patch Update. Administrators should apply the latest security patches from Oracle to remediate this vulnerability. Detailed patch information is available in the Oracle Security Alert January 2024.

For systems running Oracle Java SE, upgrade to the following versions or later:

• Java SE 8u401 or later
• Java SE 11.0.22 or later
• Java SE 17.0.10 or later
• Java SE 21.0.2 or later

For Oracle GraalVM products, consult the Oracle security advisory for specific version guidance.

Additional vendor advisories are available from NetApp Security Advisory #ntap-20240201-0002 for affected NetApp products.

Workarounds

• Restrict network access to Java-based services using firewall rules or network segmentation
• Disable Java applets and Java Web Start functionality in web browsers if not required
• Implement strict input validation for all data passed to Java APIs
• Deploy web application firewalls (WAF) in front of Java-based web services to filter malicious requests

# Example: Disable Java Plugin in browsers via deployment.properties
# Create or modify deployment.properties file
echo "deployment.webjava.enabled=false" >> /etc/.java/deployment/deployment.properties
echo "deployment.javaws.enabled=false" >> /etc/.java/deployment/deployment.properties

# Verify Java version to ensure patched version is installed
java -version