CVE-2026-39842

OpenRemote is an open-source IoT platform. Versions 1.21.0 and below contain two interrelated expression injection vulnerabilities in the rules engine that allow arbitrary code execution on the server. The JavaScript rules engine executes user-supplied scripts via Nashorn's ScriptEngine.eval() without sandboxing, class filtering, or access restrictions, and the authorization check in RulesResourceImpl only restricts Groovy rules to superusers while leaving JavaScript rules unrestricted for any user with the write:rules role. Additionally, the Groovy rules engine has a GroovyDenyAllFilter security filter that is defined but never registered, as the registration code is commented out, rendering the SandboxTransformer ineffective for superuser-created Groovy rules. A non-superuser attacker with the write:rules role can create JavaScript rulesets that execute with full JVM access, enabling remote code execution as root, arbitrary file read, environment variable theft including database credentials, and complete multi-tenant isolation bypass to access data across all realms. This issue has been fixed in version 1.22.0.

OpenRemote is an open-source IoT platform. Versions 1.21.0 and below contain two interrelated expression injection vulnerabilities in the rules engine that allow arbitrary code execution on the server. The JavaScript rules engine executes user-supplied scripts via Nashorn's ScriptEngine.eval() without sandboxing, class filtering, or access restrictions, and the authorization check in RulesResourceImpl only restricts Groovy rules to superusers while leaving JavaScript rules unrestricted for any user with the write:rules role. Additionally, the Groovy rules engine has a GroovyDenyAllFilter security filter that is defined but never registered, as the registration code is commented out, rendering the SandboxTransformer ineffective for superuser-created Groovy rules. A non-superuser attacker with the write:rules role can create JavaScript rulesets that execute with full JVM access, enabling remote code execution as root, arbitrary file read, environment variable theft including database credentials, and complete multi-tenant isolation bypass to access data across all realms. This issue has been fixed in version 1.22.0.

Summary

The OpenRemote IoT platform's rules engine contains two interrelated critical expression injection vulnerabilities that allow an attacker to execute arbitrary code on the server, ultimately achieving full server compromise.

• Unsandboxed Nashorn JavaScript Engine: JavaScript rules are executed via Nashorn's ScriptEngine.eval() with user-supplied script content and no sandboxing, class filtering, or access restrictions. Critically, any non-superuser with the write:rules role can create JavaScript rulesets.
• Inactive Groovy Sandbox: The Groovy rules engine has a GroovyDenyAllFilter security filter that is defined but never registered (the registration code is commented out), rendering the SandboxTransformer ineffective. While Groovy rules are restricted to superusers, the absence of sandboxing violates the principle of defense in depth.

Details

Attacker-Controllable Source-to-Sink Paths

There are two non-superuser and two superuser exploitable attack paths from the REST API entry point to final code execution. (JavaScript × Realm/Asset + Groovy × Realm/Asset) The most critical path is detailed below.

Path 1: Unsandboxed JavaScript Expression Injection via Realm Ruleset (Non-Superuser Exploitable)

RulesetDeployment.java L368:

Object result = scriptEngine.eval(script, engineScope);

The Nashorn JavaScript engine is initialized without a ClassFilter, allowing Java.type() to access any JVM class — including java.lang.Runtime (for RCE), java.io.FileReader (for file read), and java.lang.System (for env theft).

RulesResourceImpl.java L309 (and L331, L359, L412, L437):

// VULNERABLE: only restricts Groovy, JavaScript completely unrestricted
if (ruleset.getLang() == Ruleset.Lang.GROOVY && !isSuperUser()) {
    throw new WebApplicationException(Response.Status.FORBIDDEN);
}

Non-superuser attackers with only the write:rules role can submit arbitrary JavaScript rules that execute with full JVM access.

┌─────────────────────────────────────────────────────────────────────────────────────────┐
│                          SOURCE → SINK Complete Data Flow                                │
├─────────────────────────────────────────────────────────────────────────────────────────┤
│                                                                                         │
│  ① HTTP REQUEST (Source / Entry Point)                                                   │
│  POST /api/{realm}/rules/realm                                                          │
│  Content-Type: application/json                                                         │
│  Body: { "type":"realm", "lang":"JAVASCRIPT",                                           │
│          "rules":"<MALICIOUS_SCRIPT>", ... }     ← Attacker-controlled malicious script  │
│                                                                                         │
│                              ↓ JAX-RS Deserialization                                    │
│                                                                                         │
│  ② RulesResource.createRealmRuleset()                                                   │
│     model/.../rules/RulesResource.java:153-158                                          │
│     @POST @Path("realm") @RolesAllowed("write:rules")                                   │
│     Interface: long createRealmRuleset(RequestParams, @Valid RealmRuleset ruleset)       │
│     JSON body → RealmRuleset object (Jackson deserialization)         …

OpenRemote is an open-source IoT platform. Versions 1.21.0 and below contain two interrelated expression injection vulnerabilities in the rules engine that allow arbitrary code execution on the server. The JavaScript rules engine executes user-supplied scripts via Nashorn's ScriptEngine.eval() without sandboxing, class filtering, or access restrictions, and the authorization check in RulesResourceImpl only restricts Groovy rules to superusers while leaving JavaScript rules unrestricted for any user with the write:rules role. Additionally, the Groovy rules engine has a GroovyDenyAllFilter security filter that is defined but never registered, as the registration code is commented out, rendering the SandboxTransformer ineffective for superuser-created Groovy rules. A non-superuser attacker with the write:rules role can create JavaScript rulesets that execute with full JVM access, enabling remote code execution as root, arbitrary file read, environment variable theft including database credentials, and complete multi-tenant isolation bypass to access data across all realms. This issue has been fixed in version 1.22.0.

OpenRemote is an open-source IoT platform. Versions 1.21.0 and below contain two interrelated expression injection vulnerabilities in the rules engine that allow arbitrary code execution on the server. The JavaScript rules engine executes user-supplied scripts via Nashorn's ScriptEngine.eval() without sandboxing, class filtering, or access restrictions, and the authorization check in RulesResourceImpl only restricts Groovy rules to superusers while leaving JavaScript rules unrestricted for any user with the write:rules role. Additionally, the Groovy rules engine has a GroovyDenyAllFilter security filter that is defined but never registered, as the registration code is commented out, rendering the SandboxTransformer ineffective for superuser-created Groovy rules. A non-superuser attacker with the write:rules role can create JavaScript rulesets that execute with full JVM access, enabling remote code execution as root, arbitrary file read, environment variable theft including database credentials, and complete multi-tenant isolation bypass to access data across all realms. This issue has been fixed in version 1.22.0.

Summary

The OpenRemote IoT platform's rules engine contains two interrelated critical expression injection vulnerabilities that allow an attacker to execute arbitrary code on the server, ultimately achieving full server compromise.

• Unsandboxed Nashorn JavaScript Engine: JavaScript rules are executed via Nashorn's ScriptEngine.eval() with user-supplied script content and no sandboxing, class filtering, or access restrictions. Critically, any non-superuser with the write:rules role can create JavaScript rulesets.
• Inactive Groovy Sandbox: The Groovy rules engine has a GroovyDenyAllFilter security filter that is defined but never registered (the registration code is commented out), rendering the SandboxTransformer ineffective. While Groovy rules are restricted to superusers, the absence of sandboxing violates the principle of defense in depth.

Details

Attacker-Controllable Source-to-Sink Paths

There are two non-superuser and two superuser exploitable attack paths from the REST API entry point to final code execution. (JavaScript × Realm/Asset + Groovy × Realm/Asset) The most critical path is detailed below.

Path 1: Unsandboxed JavaScript Expression Injection via Realm Ruleset (Non-Superuser Exploitable)

RulesetDeployment.java L368:

Object result = scriptEngine.eval(script, engineScope);

The Nashorn JavaScript engine is initialized without a ClassFilter, allowing Java.type() to access any JVM class — including java.lang.Runtime (for RCE), java.io.FileReader (for file read), and java.lang.System (for env theft).

RulesResourceImpl.java L309 (and L331, L359, L412, L437):

// VULNERABLE: only restricts Groovy, JavaScript completely unrestricted
if (ruleset.getLang() == Ruleset.Lang.GROOVY && !isSuperUser()) {
    throw new WebApplicationException(Response.Status.FORBIDDEN);
}

Non-superuser attackers with only the write:rules role can submit arbitrary JavaScript rules that execute with full JVM access.

┌─────────────────────────────────────────────────────────────────────────────────────────┐
│                          SOURCE → SINK Complete Data Flow                                │
├─────────────────────────────────────────────────────────────────────────────────────────┤
│                                                                                         │
│  ① HTTP REQUEST (Source / Entry Point)                                                   │
│  POST /api/{realm}/rules/realm                                                          │
│  Content-Type: application/json                                                         │
│  Body: { "type":"realm", "lang":"JAVASCRIPT",                                           │
│          "rules":"<MALICIOUS_SCRIPT>", ... }     ← Attacker-controlled malicious script  │
│                                                                                         │
│                              ↓ JAX-RS Deserialization                                    │
│                                                                                         │
│  ② RulesResource.createRealmRuleset()                                                   │
│     model/.../rules/RulesResource.java:153-158                                          │
│     @POST @Path("realm") @RolesAllowed("write:rules")                                   │
│     Interface: long createRealmRuleset(RequestParams, @Valid RealmRuleset ruleset)       │
│     JSON body → RealmRuleset object (Jackson deserialization)         …