CVE-2026-75520: Domoticz: Missing authorization and path traversal in the udevices Lua parser handler
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-11 15:49 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
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.
Description quoted from the CVE record (assigned by GitHub_M, published 2026-10-28).
Weakness: CWE-22: Improper Limitation of a Pathname to a Restricted Directory (‘Path Traversal’); CWE-862: Missing Authorization
How it can be exploited
Exploitable over the network with low attack complexity needing low privileges and no user interaction. Impact: confidentiality low, integrity low, availability none. CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
CISA assessment (SSVC): CISA has no evidence of exploitation. Automatable: no. Technical impact: partial.
Public exploit evidence (Exploit Observer)
Exploit Observer found 3 code repositories naming this CVE.
Code repositories that name a CVE are often scanners, copies or fakes, and some are malware. Read the code before running anything.
See all 4 references on Exploit Observer
Live scores
- EPSS
- 0.003
low predicted chance of attack - VEDAS
- 0.988
strong exploit evidence - On CISA KEV
- Not listed
- Detection rule
- Suricata
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| domoticz | version <= 2026.2 | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
How to fix it
No fixed version or vendor advisory is listed in the CVE record yet. Watch the vendor’s security page.
How to detect it
Suricata rules (network detection)
1 rule that alert on traffic matching this exploit: VEDAS CVE-2026-75520 Domoticz - udevices Lua Parser Missing Authorization Path Traversal Attempt. Add them to your Suricata rule set and reload.
Show the rules
alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2026-75520 Domoticz - udevices Lua Parser Missing Authorization Path Traversal Attempt"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/json.htm"; nocase; content:"param=udevices"; nocase; fast_pattern; content:"script="; nocase; pcre:"/script=[^&]*(\.\.(\/|%2[fF]|\x5c)|%2[eE]%2[eE])/i"; classtype:web-application-attack; reference:cve,CVE-2026-75520; reference:url,https://www.exploit.observer/?keyword=CVE-2026-75520&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=domoticz&match=exact; sid:1105004; rev:1;)
CVE-2026-75520.rules on GitHub
References
Other references
- https://github.com/domoticz/domoticz/security/advisories/GHSA-8rv5-x8wv-c5c4 (x_refsource_CONFIRM)
- https://github.com/domoticz/domoticz/commit/73ed0495af6de3309f27cfc0091e803300ab5ccd (x_refsource_MISC)
- https://github.com/domoticz/domoticz/blob/2026.3/main/WebServerCmds.cpp#L3445-L3451 (x_refsource_MISC)
- https://github.com/domoticz/domoticz/releases/tag/2026.3 (x_refsource_MISC)
- https://github.com/domoticz/libwebem/blob/dfe946fa32f4c211662e47ef55b8cedfc50a6a76/include/libwebem/session.h#L10-L17 (x_refsource_MISC)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.
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