CVE-2024-21210: Oracle JDK Hotspot RCE Vulnerability

CVE-2024-21210 Overview

CVE-2024-21210 is a vulnerability in the Oracle Java SE Hotspot component that allows an unauthenticated attacker with network access via multiple protocols to compromise Oracle Java SE. This vulnerability affects several Java versions including Java SE 8u421, 8u421-perf, 11.0.24, 17.0.12, 21.0.4, and 23. The Hotspot component is a core part of the Java Virtual Machine (JVM) responsible for just-in-time (JIT) compilation and runtime optimizations.

Critical Impact

Successful exploitation can result in unauthorized update, insert, or delete access to some Oracle Java SE accessible data. The vulnerability can be exploited through APIs in the Hotspot component, including via web services, and also affects sandboxed Java Web Start applications and Java applets that load untrusted code.

Affected Products

• Oracle JDK 8u421, 8u421-perf (Enterprise Performance Pack)
• Oracle JDK 11.0.24, 17.0.12, 21.0.4, and 23
• Oracle JRE 8u421, 8u421-perf, 11.0.4, 17.0.12, 21.0.4, and 23

Discovery Timeline

• 2024-10-15 - CVE-2024-21210 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2024-21210

Vulnerability Analysis

This vulnerability is classified under CWE-203 (Observable Discrepancy), commonly known as a side channel attack vulnerability. The flaw exists within the Hotspot component of Oracle Java SE, which is responsible for executing Java bytecode and performing just-in-time compilation optimizations.

The vulnerability enables information leakage through observable behavioral discrepancies in the Hotspot component's execution. While the attack requires network access and is considered difficult to exploit due to the high attack complexity, it does not require privileges or user interaction. The integrity impact allows attackers to perform unauthorized data modifications, though confidentiality and availability remain unaffected.

Root Cause

The root cause stems from an observable discrepancy vulnerability (CWE-203) in the Hotspot component. This type of weakness occurs when the product behaves differently or returns different responses in a way that reveals security-relevant information about the state of the product. In this case, the Hotspot JIT compiler or runtime exhibits timing or behavioral differences that can be measured and exploited by an attacker to infer internal state information.

Attack Vector

The vulnerability can be exploited remotely over the network through multiple protocols. Attack scenarios include:

1. API-based exploitation: An attacker can craft malicious inputs to web services that interact with the vulnerable Hotspot component APIs, observing response variations to extract information or manipulate data.

2. Sandboxed applet exploitation: In environments where sandboxed Java Web Start applications or Java applets are permitted to execute untrusted code from the internet, malicious code can exploit the timing discrepancies within the sandbox to bypass security restrictions.

3. Web service attacks: Services that supply data to affected Java APIs can be leveraged as attack vectors, with the attacker observing behavioral differences to gain unauthorized data modification capabilities.

The exploitation is considered difficult due to the precision required in measuring and exploiting the observable discrepancies, but successful attacks can compromise data integrity within the affected Java SE deployment.

Detection Methods for CVE-2024-21210

Indicators of Compromise

• Unusual network traffic patterns to Java-based web services with repetitive, precisely-timed requests
• Anomalous JVM behavior including unexpected data modifications in Java applications
• Evidence of untrusted Java applet or Web Start application execution from external sources

Detection Strategies

• Monitor Java application logs for unusual API access patterns or repeated requests with minor variations
• Implement network-level monitoring for suspicious traffic to endpoints running vulnerable Java SE versions
• Deploy application performance monitoring to detect timing anomalies in Hotspot JIT compilation behavior
• Enable Java security manager logging to track sandbox boundary interactions

Monitoring Recommendations

• Establish baselines for normal Java application response times and alert on statistical anomalies
• Monitor for execution of Java Web Start applications or applets from untrusted sources
• Review web service logs for patterns consistent with side-channel enumeration attempts
• Implement SentinelOne endpoint protection with behavioral detection for Java process anomalies

How to Mitigate CVE-2024-21210

Immediate Actions Required

• Update all Oracle JDK and JRE installations to the latest patched versions released in the October 2024 Critical Patch Update
• Audit all systems for affected Java SE versions: 8u421, 8u421-perf, 11.0.24, 17.0.12, 21.0.4, and 23
• Disable Java Web Start and Java applets where not required for business operations
• Review and restrict network access to Java-based web services from untrusted networks

Patch Information

Oracle has released patches for this vulnerability as part of the October 2024 Critical Patch Update. Organizations should apply the following updates:

• Java SE 8: Update to versions later than 8u421
• Java SE 11: Update to versions later than 11.0.24
• Java SE 17: Update to versions later than 17.0.12
• Java SE 21: Update to versions later than 21.0.4
• Java SE 23: Apply the October 2024 CPU patch

Debian-based systems should refer to the Debian LTS security announcements for distribution-specific patch guidance.

Workarounds

• Restrict execution of untrusted Java code by disabling Java Web Start and browser plugins where possible
• Implement strict code signing requirements for all Java applications and applets
• Use network segmentation to limit exposure of Java-based services to trusted networks only
• Consider deploying a Web Application Firewall (WAF) to filter suspicious requests to Java web services

# Configuration example - Disable Java Web Start associations
# Remove or rename the javaws executable to prevent Web Start execution
sudo mv /usr/lib/jvm/java-*/bin/javaws /usr/lib/jvm/java-*/bin/javaws.disabled

# Verify Java version and identify vulnerable installations
java -version
find /usr -name "java" -type f -exec {} -version \; 2>&1 | grep -E "1.8.0_421|11.0.24|17.0.12|21.0.4|23"