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

Status: published. Published: 2026-10-28. Updated: 2026-11-03.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- domoticz / domoticz: <= 2026.2 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 5.4 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: 0.28% as of 2026-11-02; percentile 20.40%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-22, CWE-862

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/domoticz/domoticz/security/advisories/GHSA-8rv5-x8wv-c5c4 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/domoticz/domoticz/commit/73ed0495af6de3309f27cfc0091e803300ab5ccd (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/domoticz/domoticz/blob/2026.3/main/WebServerCmds.cpp#L3445-L3451 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/domoticz/domoticz/releases/tag/2026.3 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/domoticz/libwebem/blob/dfe946fa32f4c211662e47ef55b8cedfc50a6a76/include/libwebem/session.h#L10-L17 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-75520; retrieved 2026-11-03; source updated 2026-11-03

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-75520; retrieved 2026-11-03; source updated Not reported

Revision: 46c677559d8a13cde415502175d9753d94e7a1a829f8e1e363d881a5a3b01f23

Canonical: https://y2.dev/cve/CVE-2026-75520

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