CVE-2020-14583: Oracle OpenJDK RCE Vulnerability

CVE-2020-14583 Overview

CVE-2020-14583 is a sandbox escape vulnerability affecting the Libraries component of Oracle Java SE and Java SE Embedded. This vulnerability enables an unauthenticated attacker with network access to completely compromise affected Java deployments that run untrusted code within the Java sandbox environment. The vulnerability is particularly dangerous for client-side Java deployments running sandboxed Java Web Start applications or Java applets that load and execute code from untrusted sources such as the internet.

Successful exploitation requires user interaction and network access via multiple protocols, but when achieved, can result in complete takeover of the affected Java environment with potential to significantly impact additional products beyond the compromised Java instance.

Critical Impact

Complete compromise of Java SE and Java SE Embedded environments running sandboxed untrusted code, enabling attackers to escape sandbox restrictions and gain full control of the Java deployment with impacts to confidentiality, integrity, and availability.

Affected Products

• Oracle JDK 7u261, 8u251, 11.0.7, and 14.0.1
• Oracle JRE 7u261, 8u251, 11.0.7, and 14.0.1
• Oracle OpenJDK versions 7 through 14
• Java SE Embedded 8u251
• Fedora 31 and 32
• Canonical Ubuntu Linux 16.04, 18.04, and 20.04
• Debian Linux 9.0 and 10.0
• openSUSE Leap 15.1 and 15.2
• NetApp Active IQ Unified Manager, Cloud Backup, Cloud Secure Agent, and other NetApp products

Discovery Timeline

• July 15, 2020 - CVE-2020-14583 published to NVD
• May 27, 2025 - Last updated in NVD database

Technical Details for CVE-2020-14583

Vulnerability Analysis

This vulnerability exists within the Libraries component of Java SE and allows attackers to bypass Java sandbox security restrictions. The Java sandbox is designed to isolate untrusted code and prevent it from accessing system resources or performing privileged operations. When this sandbox is compromised, code that should be restricted gains elevated capabilities.

The attack requires network access and human interaction, typically achieved by convincing a user to visit a malicious website that hosts a specially crafted Java Web Start application or Java applet. Once the user executes the malicious Java code, the attacker can escape the sandbox and execute arbitrary operations with the privileges of the Java process.

It is important to note that this vulnerability specifically targets client-side Java deployments that execute untrusted code. Server-side Java deployments that only load and run trusted, administrator-installed code are not affected by this vulnerability.

Root Cause

The vulnerability stems from an unspecified flaw in the Libraries component of Java SE. The underlying issue allows specially crafted untrusted Java code to circumvent sandbox restrictions that are designed to contain and limit the capabilities of applets and Web Start applications. This type of vulnerability typically involves improper access control, type confusion, or security check bypasses within the core Java libraries that enforce sandbox policies.

Attack Vector

The attack vector for CVE-2020-14583 is network-based and requires user interaction:

1. An attacker hosts a malicious Java Web Start application or Java applet on a web server
2. The attacker entices a victim to visit the malicious website or click a link
3. The victim's browser loads and executes the untrusted Java code within the sandbox
4. The malicious code exploits the vulnerability to escape the sandbox
5. Once sandbox restrictions are bypassed, the attacker gains full control over the Java deployment and potentially the underlying system

The attack is described as difficult to exploit, indicating that successful exploitation requires specific conditions or sophisticated techniques. However, successful attacks can impact additional products beyond the compromised Java environment, increasing the scope of potential damage.

Detection Methods for CVE-2020-14583

Indicators of Compromise

• Unusual Java process behavior including unexpected network connections or file system access from sandboxed applications
• Java Web Start or applet processes spawning child processes or executing system commands
• Anomalous Java application activity attempting to access restricted system resources or directories
• Log entries indicating sandbox policy violations or security exception bypasses

Detection Strategies

• Monitor for Java Web Start (javaws) and applet plugin processes making suspicious system calls or network connections
• Implement application whitelisting to prevent execution of unapproved Java applications
• Enable Java security logging and monitor for SecurityException events and access control violations
• Deploy endpoint detection solutions capable of identifying Java sandbox escape attempts

Monitoring Recommendations

• Configure centralized logging for Java security events across all endpoints
• Monitor network traffic for connections to known malicious Java applet hosting infrastructure
• Implement browser-level controls to warn or block execution of Java applets from untrusted sources
• Track Java installation versions across the environment to identify unpatched systems

How to Mitigate CVE-2020-14583

Immediate Actions Required

• Update all affected Oracle JDK and JRE installations to the latest patched versions released in the July 2020 Critical Patch Update
• Disable Java browser plugins if not required for business operations
• Restrict execution of Java Web Start applications and applets to trusted sources only
• Implement network-level controls to block access to known malicious Java content hosts

Patch Information

Oracle addressed this vulnerability in the July 2020 Critical Patch Update. Organizations should update to the following minimum versions or later:

• Java SE 7u271 or later
• Java SE 8u261 or later
• Java SE 11.0.8 or later
• Java SE 14.0.2 or later

Security updates are also available from Linux distribution vendors including Debian, Ubuntu, Fedora, and openSUSE. NetApp customers should refer to the NetApp Security Advisory NTAP-20200717-0005 for guidance on affected products.

Workarounds

• Disable Java browser plugins entirely using browser security settings or group policy
• Configure Java security settings to block execution of unsigned or self-signed applets
• Use the Java Deployment Rule Set to whitelist only approved Java Web Start applications
• Implement network filtering to prevent users from accessing untrusted Java content

# Disable Java plugin in deployment.properties
# Add these settings to deployment.properties file
deployment.webjava.enabled=false
deployment.javaws.enabled=false
deployment.security.level=VERY_HIGH