CVE-2025-32406: NAKIVO Backup & Replication XXE Vulnerability

CVE-2025-32406 Overview

CVE-2025-32406 is a critical XML External Entity (XXE) vulnerability affecting the Director NBR component in NAKIVO Backup & Replication software. This vulnerability allows remote attackers to exploit improper XML parsing to fetch and parse arbitrary XML responses, potentially leading to unauthorized access to sensitive data, server-side request forgery (SSRF), or information disclosure from the affected system.

XXE vulnerabilities occur when an application processes XML input containing references to external entities without proper validation. In the context of backup and replication software, this type of vulnerability poses a significant risk as these systems typically have broad network access and may contain sensitive configuration data, credentials, and access to critical infrastructure.

Critical Impact

Remote attackers can exploit this XXE vulnerability to access sensitive files, perform SSRF attacks, or exfiltrate confidential information from NAKIVO Backup & Replication servers without authentication.

Affected Products

• NAKIVO Backup & Replication versions 10.3.x through 11.0.1
• Director NBR component across affected versions
• All installations running vulnerable versions prior to 11.0.2

Discovery Timeline

• 2025-04-08 - CVE-2025-32406 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-32406

Vulnerability Analysis

The vulnerability resides in the Director NBR component of NAKIVO Backup & Replication. The component fails to properly sanitize or disable external entity references when processing XML input, creating an XXE (XML External Entity Injection) attack surface. This weakness is classified under CWE-611 (Improper Restriction of XML External Entity Reference).

When an attacker submits specially crafted XML data containing external entity declarations to the vulnerable component, the XML parser processes these entities without restriction. This enables the attacker to reference external resources, including local files on the server, internal network resources, or external URLs controlled by the attacker.

The vulnerability is particularly concerning in backup infrastructure contexts where the affected software likely has privileged access to multiple systems and may store or process sensitive credentials and configuration data.

Root Cause

The root cause of this vulnerability is the improper configuration of the XML parser in the Director NBR component. The parser does not disable Document Type Definitions (DTD) processing or restrict the resolution of external entities. When XML input is received, the parser follows entity references without validating their source or content, allowing attackers to define malicious external entities that point to sensitive resources.

Secure XML parsing requires explicitly disabling DTD processing and external entity resolution. The absence of these security controls in the affected NAKIVO component creates the attack vector exploited by CVE-2025-32406.

Attack Vector

This vulnerability is exploitable over the network without requiring authentication or user interaction. An attacker can craft malicious XML payloads containing external entity declarations that, when processed by the vulnerable Director NBR component, force the server to:

1. Read and return the contents of local files (e.g., /etc/passwd, configuration files, credentials)
2. Make HTTP requests to internal services (SSRF)
3. Perform port scanning of internal network resources
4. Exfiltrate data to attacker-controlled servers via out-of-band (OOB) techniques

The attack can be executed by sending a malicious XML document to the Director NBR component's XML processing endpoint. The attacker defines an external entity pointing to a target resource, and when the XML is parsed, the content of that resource is included in the response or transmitted out-of-band.

For detailed technical information about the vulnerability mechanism and attack scenarios, refer to the NAKIVO Security Advisory.

Detection Methods for CVE-2025-32406

Indicators of Compromise

• Unusual XML requests to Director NBR component containing DOCTYPE declarations or ENTITY definitions
• Server-side requests originating from NAKIVO servers to unexpected internal or external destinations
• Log entries showing access to sensitive files like /etc/passwd, /etc/shadow, or application configuration files
• Outbound connections to suspicious domains or IP addresses from the NAKIVO server

Detection Strategies

• Monitor network traffic to and from NAKIVO Backup & Replication servers for anomalous XML payloads
• Implement web application firewall (WAF) rules to detect and block XXE attack patterns in incoming requests
• Enable verbose logging on the Director NBR component and review logs for suspicious XML parsing activities
• Deploy intrusion detection systems (IDS) with signatures for XXE exploitation attempts

Monitoring Recommendations

• Establish baseline network behavior for NAKIVO servers and alert on deviations, particularly unexpected outbound connections
• Monitor file access patterns on the NAKIVO server for reads of sensitive system or configuration files
• Implement SIEM rules to correlate XML-related events with potential data exfiltration indicators
• Regularly audit NAKIVO server logs for unauthorized access attempts or unusual API calls

How to Mitigate CVE-2025-32406

Immediate Actions Required

• Upgrade NAKIVO Backup & Replication to version 11.0.2 or later immediately
• Isolate NAKIVO servers from untrusted networks until patching is complete
• Review server logs for indicators of compromise or exploitation attempts
• Implement network segmentation to limit the blast radius of potential compromise

Patch Information

NAKIVO has addressed this vulnerability in version 11.0.2 of Backup & Replication. Organizations running versions 10.3.x through 11.0.1 should upgrade to the patched version as soon as possible. The security fix properly configures the XML parser to disable DTD processing and external entity resolution.

For detailed patch information and upgrade instructions, refer to the NAKIVO Security Advisory for CVE-2025-32406.

Workarounds

• Deploy a web application firewall (WAF) in front of NAKIVO services to filter malicious XML payloads
• Restrict network access to the Director NBR component using firewall rules to allow only trusted IP addresses
• Implement network-level monitoring to detect and alert on potential XXE exploitation attempts
• Consider temporarily disabling external network access for the NAKIVO server until patching is completed

If immediate patching is not possible, consult the NAKIVO security advisory for additional guidance on temporary mitigations specific to your environment.