CVE-2023-25141: Apache Sling JCR Base RCE Vulnerability

CVE-2023-25141 Overview

CVE-2023-25141 is a critical injection vulnerability affecting Apache Sling JCR Base versions prior to 3.1.12 when running on older JDK versions (JDK 1.8.191 or earlier). The vulnerability exists in utility functions within the RepositoryAccessor class, specifically the getRepository and getRepositoryFromURL functions. These functions allow an application to access data stored in remote locations via JNDI (Java Naming and Directory Interface) and RMI (Remote Method Invocation), creating an avenue for attackers to exploit injection weaknesses.

Critical Impact

Attackers can leverage JNDI/RMI injection to access sensitive data from remote locations, potentially leading to unauthorized information disclosure on vulnerable systems running legacy JDK versions.

Affected Products

• Apache Sling JCR Base versions prior to 3.1.12
• Systems running JDK 1.8.191 or earlier
• Applications utilizing RepositoryAccessor utility functions

Discovery Timeline

• 2023-02-14 - CVE-2023-25141 published to NVD
• 2025-03-20 - Last updated in NVD database

Technical Details for CVE-2023-25141

Vulnerability Analysis

This vulnerability falls under CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), commonly referred to as injection. The flaw resides in the RepositoryAccessor class, which provides utility functions for accessing JCR (Java Content Repository) repositories.

The vulnerable functions getRepository and getRepositoryFromURL fail to properly sanitize input when handling JNDI and RMI lookups. When deployed on older JDK versions (specifically JDK 1.8.191 or earlier), the insufficient protections against JNDI injection attacks present in those legacy Java versions compound the vulnerability, enabling attackers to potentially redirect lookups to malicious remote servers.

The network-based attack vector requires no privileges or user interaction, making it particularly concerning for internet-facing deployments. Successful exploitation could result in unauthorized access to confidential data stored in connected repositories.

Root Cause

The root cause stems from inadequate input validation in the RepositoryAccessor utility functions when processing repository URLs. The functions getRepository and getRepositoryFromURL do not sufficiently sanitize or validate the URL parameters before initiating JNDI/RMI lookups. This oversight, combined with the weaker JNDI security controls in older JDK versions, creates the injection vulnerability.

Older JDK versions prior to 1.8.191 lack critical security patches that restrict JNDI lookups to trusted sources, making applications running on these legacy runtimes particularly susceptible to JNDI injection attacks.

Attack Vector

The attack leverages the network-accessible RepositoryAccessor utility functions. An attacker can craft malicious JNDI or RMI URLs that, when processed by the vulnerable getRepository or getRepositoryFromURL functions, redirect the application to attacker-controlled servers. This can result in:

1. Remote data exfiltration through manipulated JNDI lookups
2. Access to sensitive repository information
3. Potential for further exploitation depending on the application context

The vulnerability requires the target system to be running on JDK 1.8.191 or earlier, as newer JDK versions include security mitigations that restrict JNDI remote class loading by default.

Detection Methods for CVE-2023-25141

Indicators of Compromise

• Unusual outbound JNDI or RMI connections from Apache Sling applications
• Unexpected network traffic to external LDAP, RMI, or DNS servers from JCR Base components
• Application logs showing suspicious repository access attempts with non-standard URLs
• Evidence of RepositoryAccessor methods being invoked with external or untrusted URL patterns

Detection Strategies

• Monitor application logs for calls to getRepository and getRepositoryFromURL with suspicious URL parameters containing JNDI schemes (ldap://, rmi://, dns://)
• Implement network monitoring to detect outbound connections from Sling applications to unexpected external hosts
• Deploy runtime application self-protection (RASP) solutions to detect JNDI injection attempts
• Use SentinelOne Singularity to identify anomalous process behavior and network connections associated with Java applications

Monitoring Recommendations

• Enable detailed logging for JCR repository access operations
• Implement alerting for any JNDI/RMI lookups to external domains
• Monitor JVM process network activity for connections outside expected repository infrastructure
• Audit JDK versions across environments to identify systems still running vulnerable JDK releases

How to Mitigate CVE-2023-25141

Immediate Actions Required

• Upgrade Apache Sling JCR Base to version 3.1.12 or later immediately
• If immediate patching is not possible, upgrade the JDK to a version newer than 1.8.191
• Audit all applications using RepositoryAccessor utility functions for potential exposure
• Implement network segmentation to restrict outbound JNDI/RMI connections from application servers

Patch Information

Apache has released version 3.1.12 of Sling JCR Base which addresses this vulnerability. Users are strongly recommended to upgrade to this version or later. For systems where immediate upgrades are not feasible, running on a more recent JDK provides mitigation as newer JDK versions include security restrictions on JNDI remote class loading.

Official patch information and updates are available through the Apache Sling News Updates.

Workarounds

• Upgrade to JDK versions newer than 1.8.191 which include JNDI security restrictions
• Implement network-level controls to block outbound LDAP, RMI, and suspicious DNS traffic from application servers
• Use a web application firewall (WAF) to filter requests containing JNDI injection patterns
• Restrict access to the affected RepositoryAccessor methods through application-level access controls

# Example: Check current JDK version
java -version

# Ensure JDK is newer than 1.8.0_191 or upgrade Apache Sling JCR Base
# Verify installed Sling JCR Base version in your Maven dependencies
mvn dependency:tree | grep sling-jcr-base