Bug 2563234 (CVE-2026-75520)

Summary: CVE-2026-75520 domoticz: domoticz: Unauthorized script execution via missing permission checks
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Domoticz. Missing authorization checks allow low-privileged authenticated users to execute existing server scripts with attacker-controlled input. The application's device update command handler fails to validate user permissions before invoking Lua scripts and does not properly restrict script file paths. A remote authenticated attacker can exploit this issue by submitting a crafted web request, resulting in unauthorized script execution and potential data modification.
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Description OSIDB Bzimport 2026-10-28 22:41:33 UTC 
Domoticz is a free, open source home automation system for Linux, Windows, macOS, and Raspberry Pi. Prior to 2026.3, the `udevices` JSON command handler, `Cmd_UpdateDevices` in `main/WebServerCmds.cpp`, performed no `session.rights` check before invoking a Lua parser script, while its sibling command handlers gate access by role. A low-privilege authenticated user could trigger execution of an existing operator-installed Lua parser script with attacker-controlled input through the `GET /json.htm` endpoint with `type=command` and `param=udevices`. The `script` parameter also lacked a `..` path-traversal guard: `CLuaHandler::executeLuaScript` in `main/LuaHandler.cpp` constructed the filename from the parser directory and the supplied script name before passing it to `luaL_loadfile`. Execution is limited to already-installed valid Lua files; this is not arbitrary code execution, and the advisory states that file-write and upload paths require administrator privileges. This issue is addressed in version 2026.3.