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CVE-2026-39842 affects OpenRemote 1.21.0 and earlier and consists of two related expression injection flaws in the rules engine that permit arbitrary server-side code execution. In the JavaScript rules engine, user-supplied rule scripts are executed through Nashorn ScriptEngine.eval() without sandboxing, class filtering, or other access restrictions. In parallel, the authorization logic in RulesResourceImpl restricts Groovy rule creation to superusers but leaves JavaScript rules available to any user holding the write:rules role. Separately, the Groovy rules engine includes a GroovyDenyAllFilter, but the filter is never registered because the registration code is commented out, which leaves the intended SandboxTransformer protections ineffective for superuser-created Groovy rules. As a result, an attacker able to create JavaScript rules can execute arbitrary code with full JVM access on the OpenRemote server.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
Repository contains a small, focused exploit set for CVE-2026-39842 against OpenRemote Rules Engine. Structure: one README with vulnerability write-up and usage guidance, one Python detector, one Python exploit PoC, and one Nmap NSE detector. Languages are Python, Lua, and Markdown. Main exploit capability is in exploit_openremote.py. It is an authenticated web/network RCE PoC targeting OpenRemote <= 1.21.0. The script logs into OpenRemote’s Keycloak endpoint using username/password and client_id=openremote, checks version via /api/master/info, then abuses the rules API by creating a JavaScript ruleset at /api/{realm}/rules/realm. The payload relies on Nashorn JavaScript access to Java.type()/Runtime.exec(), yielding command execution as root. The CLI exposes practical modes for whoami/id checks, arbitrary command execution, file reads, and environment-variable dumping, and includes optional cleanup of the malicious ruleset. The repository also includes two detection components. detect_openremote.py is a standalone Python scanner that fingerprints OpenRemote via /api/master/info and the main page, extracts version information, and checks rules API accessibility to determine likely vulnerability status. openremote-detect.nse is an Nmap NSE vulnerability detection script that performs similar safe checks and reports VULN/NOT_VULN/LIKELY_VULN states. Because this is an NSE-based repository component, framework identification is set to nmap_nse, but the repo is not solely a framework module; it also contains standalone Python code. Fingerprintable targets and endpoints center on OpenRemote web APIs: /api/master/info, /api/master/rules/realm, /api/{realm}/rules/realm, /api/{realm}/rules/asset, and /auth/realms/{realm}/protocol/openid-connect/token. Example sensitive file targets include /etc/passwd and /etc/shadow. Overall, this is a legitimate exploit repository combining safe detection and an authenticated operational PoC for server-side RCE.
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