CVE-2025-4447: Eclipse OpenJ9 Buffer Overflow Vulnerability

CVE-2025-4447 Overview

CVE-2025-4447 is a stack-based buffer overflow vulnerability affecting Eclipse OpenJ9 versions up to 0.51 when used with OpenJDK version 8. The vulnerability can be triggered by modifying a specific file on disk that is read during JVM startup, potentially allowing an attacker with local access to cause a buffer overflow condition.

Critical Impact

A local attacker with the ability to modify files read during JVM startup can trigger a stack-based buffer overflow, potentially leading to high integrity and availability impact on the affected system.

Affected Products

• Eclipse OpenJ9 versions up to 0.51
• OpenJDK version 8 (when used with affected OpenJ9 versions)

Discovery Timeline

• 2025-05-09 - CVE-2025-4447 published to NVD
• 2025-09-05 - Last updated in NVD database

Technical Details for CVE-2025-4447

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow). The flaw exists in the Eclipse OpenJ9 JVM implementation when parsing or processing certain files that are read during the JVM initialization phase. When Eclipse OpenJ9 is paired with OpenJDK version 8, the vulnerable code path can be triggered by a maliciously crafted or modified file present on the local system.

The local attack vector requires an attacker to have prior access to the system to modify the target file before the JVM starts. This represents a pre-exploitation scenario where file manipulation serves as the attack trigger mechanism.

Root Cause

The root cause is improper bounds checking when reading file contents into a stack-allocated buffer during JVM startup. The Eclipse OpenJ9 runtime fails to adequately validate the size of input data from certain configuration or initialization files, allowing data to overflow the allocated stack buffer when the file contents exceed expected boundaries.

Attack Vector

The attack requires local access to the target system with sufficient privileges to modify files that the JVM reads during startup. An attacker would need to:

1. Identify the specific file(s) read by OpenJ9 during initialization
2. Craft malicious content designed to overflow the stack buffer
3. Modify or replace the target file with the malicious version
4. Wait for or trigger a JVM restart to execute the overflow

The local attack vector with low privilege requirements means that any user with write access to the affected files could potentially exploit this vulnerability. The stack-based nature of the overflow could potentially be leveraged for code execution, though successful exploitation may be complicated by modern exploit mitigations.

Detection Methods for CVE-2025-4447

Indicators of Compromise

• Unexpected JVM crashes or segmentation faults during startup with OpenJ9 and OpenJDK 8
• Unusual modifications to configuration files read by the JVM during initialization
• Stack smashing or buffer overflow errors in system logs associated with Java processes
• Unexplained changes in file modification timestamps for JVM-related configuration files

Detection Strategies

• Monitor file integrity of all files read by Eclipse OpenJ9 during JVM startup
• Implement endpoint detection rules for abnormal JVM process behavior, including unexpected crashes during initialization
• Deploy file system auditing to track write operations to JVM configuration directories
• Configure logging to capture detailed JVM startup errors and stack traces

Monitoring Recommendations

• Enable comprehensive logging for Java application startups, particularly for services using OpenJ9 with OpenJDK 8
• Implement real-time file integrity monitoring on critical JVM configuration files
• Set up alerts for recurring JVM crashes that occur specifically during the initialization phase
• Review system audit logs for unauthorized file modifications in JVM installation directories

How to Mitigate CVE-2025-4447

Immediate Actions Required

• Upgrade Eclipse OpenJ9 to a version beyond 0.51 that contains the security fix
• Restrict write permissions to files and directories read by the JVM during startup to prevent unauthorized modifications
• Consider migrating to a newer OpenJDK version (beyond version 8) if compatible with your application requirements
• Implement file integrity monitoring on JVM configuration and initialization files

Patch Information

Eclipse has addressed this vulnerability. The fix is tracked in the GitHub OpenJ9 Pull Request #21762. Organizations should upgrade to a patched version of Eclipse OpenJ9 that incorporates this fix. For detailed information about the vulnerability and remediation, refer to the GitLab CVE Assignment Issue.

Workarounds

• Implement strict file permissions to ensure only trusted administrators can modify files read during JVM startup
• Use file integrity monitoring solutions to detect and alert on unauthorized modifications to JVM configuration files
• Consider running Java applications in containerized environments with read-only file systems for critical configuration files
• Limit local user access on systems running vulnerable OpenJ9 configurations until patching is complete