CVE-2026-40882: OpenRemote XXE Vulnerability

CVE-2026-40882 Overview

CVE-2026-40882 is an XML External Entity (XXE) vulnerability in OpenRemote, an open-source internet-of-things platform. Prior to version 1.22.0, the Velbus asset import path parses attacker-controlled XML without explicit XXE hardening. An authenticated user who can call the import endpoint may trigger XML external entity processing, which can lead to server-side file disclosure and Server-Side Request Forgery (SSRF). The target file must be less than 1023 characters.

Critical Impact

Authenticated attackers can exploit this XXE vulnerability to read sensitive server-side files and perform SSRF attacks, potentially exposing credentials, configuration files, and internal network resources.

Affected Products

• OpenRemote IoT Platform versions prior to 1.22.0
• OpenRemote Velbus asset import functionality
• Systems utilizing the vulnerable XML parsing endpoint

Discovery Timeline

• 2026-04-22 - CVE CVE-2026-40882 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2026-40882

Vulnerability Analysis

This vulnerability is classified as CWE-611 (Improper Restriction of XML External Entity Reference). The core issue lies in the Velbus asset import functionality within OpenRemote, which accepts user-supplied XML data without implementing proper XXE defenses. When processing attacker-controlled XML input, the parser allows external entity references to be resolved, enabling malicious actors to read files from the server's filesystem or make HTTP requests to internal services.

The exploitation requires authentication, meaning an attacker must have valid credentials to access the import endpoint. However, once authenticated, the attacker can craft malicious XML payloads containing external entity declarations that reference local files or internal URLs. The vulnerability has a limitation where the target file content must be less than 1023 characters to be successfully exfiltrated.

Root Cause

The root cause of CVE-2026-40882 is the failure to properly configure the XML parser used in the Velbus asset import functionality. The parser does not disable external entity processing or implement appropriate security controls such as disabling DTD processing, which allows attackers to define and resolve external entities within their XML input. This is a common misconfiguration in applications that process XML data without security hardening.

Attack Vector

The attack vector is network-based and requires low privileges (authentication). An attacker with valid credentials to the OpenRemote platform can target the Velbus asset import endpoint by submitting a malicious XML payload. The payload would contain an external entity definition pointing to a local file (such as /etc/passwd on Linux systems) or an internal URL. When the server parses this XML, it resolves the external entity and includes the content in the response or processing context, allowing data exfiltration.

The vulnerability can be exploited for two primary purposes: file disclosure (reading sensitive configuration files, credentials, or application data) and SSRF (making requests to internal services that are not normally accessible from external networks). The SSRF capability could potentially be used to scan internal networks, access internal APIs, or interact with cloud metadata services.

Detection Methods for CVE-2026-40882

Indicators of Compromise

• Unusual XML payloads in HTTP requests to the Velbus import endpoint containing <!DOCTYPE> declarations or <!ENTITY> definitions
• Server-side file access attempts to sensitive paths like /etc/passwd, application configuration files, or credential stores
• Outbound HTTP connections from the server to unexpected internal IP addresses or cloud metadata endpoints (e.g., 169.254.169.254)
• Error messages in application logs referencing external entity resolution failures or file access denials

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block XML requests containing external entity declarations or DTD references
• Monitor HTTP request bodies to the import endpoint for suspicious XML structures including <!ENTITY, SYSTEM, or PUBLIC keywords
• Configure SentinelOne Singularity Platform to monitor for unusual file read operations by the OpenRemote application process
• Deploy network monitoring to detect SSRF attempts by identifying outbound connections from web application servers to internal resources

Monitoring Recommendations

• Enable detailed logging on the OpenRemote application to capture all import endpoint requests with full request bodies
• Set up alerts for any file access operations by the application to sensitive directories outside the expected application scope
• Monitor DNS queries from the application server for internal hostname resolution that may indicate SSRF reconnaissance
• Review authentication logs to identify any unusual access patterns to accounts with import permissions

How to Mitigate CVE-2026-40882

Immediate Actions Required

• Upgrade OpenRemote to version 1.22.0 or later immediately, as this version contains the security fix
• If immediate upgrade is not possible, restrict access to the Velbus import endpoint through network-level controls or access control lists
• Audit user accounts with access to the import functionality and revoke unnecessary permissions
• Review application logs for any historical exploitation attempts prior to patching

Patch Information

OpenRemote version 1.22.0 fixes this vulnerability by implementing proper XXE hardening in the XML parser used for the Velbus asset import functionality. Organizations should upgrade to this version or later to remediate the issue. Additional details are available in the GitHub Security Advisory.

Workarounds

• Implement a web application firewall rule to block XML requests containing DTD declarations or external entity references to the affected endpoint
• Temporarily disable the Velbus import functionality if it is not critical to operations until the patch can be applied
• Apply network segmentation to limit the impact of potential SSRF attacks by restricting what internal resources the application server can access
• Use SentinelOne's application control features to monitor and restrict file system access by the OpenRemote application

# Example: Disable DTD processing in XML parser configuration
# This is a general example - actual implementation depends on the XML parser used
# Consult OpenRemote documentation or the security advisory for specific guidance
# Upgrade to version 1.22.0 for the official fix