CVE-2025-23195: Apache Ambari XXE Vulnerability

CVE-2025-23195 Overview

An XML External Entity (XXE) vulnerability exists in the Apache Ambari/Oozie project, allowing an attacker to inject malicious XML entities. This vulnerability occurs due to insecure parsing of XML input using the DocumentBuilderFactory class without disabling external entity resolution. An attacker can exploit this vulnerability to read arbitrary files on the server or perform server-side request forgery (SSRF) attacks. The issue has been fixed in both Ambari 2.7.9 and the trunk branch.

Critical Impact

Unauthenticated remote attackers can exploit this XXE vulnerability to read arbitrary files from the server or leverage SSRF to access internal network resources, potentially exposing sensitive configuration files, credentials, and internal services.

Affected Products

• Apache Ambari (versions prior to 2.7.9)
• Apache Oozie (component within Ambari)

Discovery Timeline

• 2025-01-21 - CVE CVE-2025-23195 published to NVD
• 2025-06-09 - Last updated in NVD database

Technical Details for CVE-2025-23195

Vulnerability Analysis

This XXE vulnerability stems from unsafe XML processing within the Apache Ambari and Oozie projects. The application utilizes Java's DocumentBuilderFactory class to parse XML input without implementing proper security configurations to disable external entity resolution. This oversight allows attackers to craft malicious XML payloads containing external entity declarations that the parser will process and resolve.

The vulnerability is classified under CWE-611 (Improper Restriction of XML External Entity Reference), which represents a fundamental failure to properly configure XML parsers against XXE attacks. The network-accessible attack vector allows unauthenticated remote attackers to exploit this flaw without requiring user interaction.

Root Cause

The root cause of this vulnerability lies in the insecure default configuration of the DocumentBuilderFactory XML parser. When XML parsers are instantiated without explicitly disabling features such as external general entities (XMLConstants.FEATURE_SECURE_PROCESSING), external parameter entities, and DTD processing, they become susceptible to XXE injection attacks.

In the affected Ambari/Oozie codebase, the XML parsing functionality failed to set critical security features including:

• setFeature("http://apache.org/xml/features/disallow-doctype-decl", true)
• setFeature("http://xml.org/sax/features/external-general-entities", false)
• setFeature("http://xml.org/sax/features/external-parameter-entities", false)

Attack Vector

The vulnerability is exploitable via network access where an attacker can submit crafted XML payloads to the affected Ambari/Oozie endpoints. The attack does not require authentication or user interaction, making it particularly dangerous in exposed deployments.

An attacker can exploit this vulnerability through two primary attack scenarios:

Arbitrary File Read: By crafting XML with external entity declarations pointing to local file paths (e.g., /etc/passwd, /etc/shadow, configuration files), attackers can exfiltrate sensitive server-side data through the XML response or error messages.

Server-Side Request Forgery (SSRF): By defining external entities that reference internal network URLs or cloud metadata endpoints (e.g., http://169.254.169.254/), attackers can probe internal infrastructure, access internal services, or retrieve cloud instance credentials.

The exploitation mechanism involves injecting a Document Type Definition (DTD) containing an external entity declaration within the malicious XML payload. When the vulnerable parser processes this input, it resolves the external entity reference, effectively allowing the attacker to read arbitrary files or make HTTP requests from the server's perspective.

Detection Methods for CVE-2025-23195

Indicators of Compromise

• Unusual XML payloads in application logs containing DTD declarations or <!ENTITY definitions
• Server logs showing file access attempts to sensitive paths like /etc/passwd, /etc/shadow, or application configuration files
• Outbound HTTP requests from the Ambari/Oozie server to unexpected internal IP addresses or cloud metadata endpoints
• Error messages in responses that reveal file contents or internal path information

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block XML payloads containing DTD declarations, external entity references, or suspicious patterns
• Monitor application logs for XML parsing errors that may indicate exploitation attempts
• Deploy network intrusion detection systems (IDS) with signatures for XXE attack patterns
• Analyze outbound traffic from Ambari/Oozie servers for connections to internal-only addresses or cloud metadata services

Monitoring Recommendations

• Enable verbose logging for XML processing components within Ambari/Oozie to capture potential exploitation attempts
• Set up alerts for any outbound connections from the Ambari server to metadata endpoints (169.254.169.254) or internal network ranges
• Monitor file access patterns on the server for reads of sensitive system files that should not be accessed by the application
• Implement application-level monitoring to track unusual XML payload sizes or structures

How to Mitigate CVE-2025-23195

Immediate Actions Required

• Upgrade Apache Ambari to version 2.7.9 or later immediately
• If immediate upgrade is not possible, implement network-level controls to restrict access to Ambari/Oozie endpoints
• Review and audit any systems that may have been exposed to identify potential data exfiltration
• Apply WAF rules to filter malicious XML payloads while preparing for the upgrade

Patch Information

Apache has addressed this vulnerability in Ambari version 2.7.9 and the trunk branch. Organizations should prioritize upgrading to the patched version as the primary remediation strategy.

For additional details, refer to the Apache Mailing List Thread and the OpenWall OSS Security Update.

Workarounds

• Restrict network access to Ambari/Oozie management interfaces using firewall rules to trusted IP addresses only
• Implement a reverse proxy with XML filtering capabilities to strip DTD declarations and external entity references from incoming requests
• If source code modification is possible, manually configure DocumentBuilderFactory instances to disable external entity processing
• Deploy application-layer controls to validate and sanitize XML input before processing

# Configuration example - Network restriction for Ambari access
# Restrict Ambari server access to trusted management network only
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP

# Enable logging for dropped connection attempts
iptables -A INPUT -p tcp --dport 8080 -j LOG --log-prefix "AMBARI_BLOCKED: "