fix: The client IP address may be determined incorrectly in some cases; this fixes a security vulnerability in which the Parse Server option masterKeyIps may be circumvented, see [GHSA-vm5r-c87r-pf6x](https://github.com/parse-community/parse-server/security/advisories/GHSA-vm5r-c87r-pf6x) (#8372)

BREAKING CHANGE: The mechanism to determine the client IP address has been rewritten; to correctly determine the IP address it is now required to set the Parse Server option `trustProxy` accordingly if Parse Server runs behind a proxy server, see the express framework's [trust proxy](https://expressjs.com/en/guide/behind-proxies.html) setting (#8372)

src/Options/Definitions.js

@@ -486,6 +486,13 @@ module.exports.ParseServerOptions = {
     help: 'Starts the liveQuery server',
     action: parsers.booleanParser,
   },
+  trustProxy: {
+    env: 'PARSE_SERVER_TRUST_PROXY',
+    help:
+      'The trust proxy settings. It is important to understand the exact setup of the reverse proxy, since this setting will trust values provided in the Parse Server API request. See the <a href="https://expressjs.com/en/guide/behind-proxies.html">express trust proxy settings</a> documentation. Defaults to `false`.',
+    action: parsers.objectParser,
+    default: [],
+  },
   userSensitiveFields: {
     env: 'PARSE_SERVER_USER_SENSITIVE_FIELDS',
     help:

src/Options/docs.js

@@ -89,6 +89,7 @@
  * @property {Number} sessionLength Session duration, in seconds, defaults to 1 year
  * @property {Boolean} silent Disables console output
  * @property {Boolean} startLiveQueryServer Starts the liveQuery server
+ * @property {Any} trustProxy The trust proxy settings. It is important to understand the exact setup of the reverse proxy, since this setting will trust values provided in the Parse Server API request. See the <a href="https://expressjs.com/en/guide/behind-proxies.html">express trust proxy settings</a> documentation. Defaults to `false`.
  * @property {String[]} userSensitiveFields Personally identifiable information fields in the user table the should be removed for non-authorized users. Deprecated @see protectedFields
  * @property {Boolean} verbose Set the logging to verbose
  * @property {Boolean} verifyUserEmails Set to `true` to require users to verify their email address to complete the sign-up process.<br><br>Default is `false`.

src/Options/index.js

@@ -241,6 +241,9 @@ export interface ParseServerOptions {
   cluster: ?NumberOrBoolean;
   /* middleware for express server, can be string or function */
   middleware: ?((() => void) | string);
+  /* The trust proxy settings. It is important to understand the exact setup of the reverse proxy, since this setting will trust values provided in the Parse Server API request. See the <a href="https://expressjs.com/en/guide/behind-proxies.html">express trust proxy settings</a> documentation. Defaults to `false`.
+  :DEFAULT: false */
+  trustProxy: ?any;
   /* Starts the liveQuery server */
   startLiveQueryServer: ?boolean;
   /* Live query server configuration options (will start the liveQuery server) */

src/ParseServer.js

@@ -343,6 +343,9 @@ class ParseServer {
         options
       );
     }
+    if (options.trustProxy) {
+      app.set('trust proxy', options.trustProxy);
+    }
     /* istanbul ignore next */
     if (!process.env.TESTING) {
       configureListeners(this);

src/cloud-code/Parse.Cloud.js

@@ -722,7 +722,7 @@ module.exports = ParseCloud;
  * @property {Boolean} isChallenge If true, means the current request is originally triggered by an auth challenge.
  * @property {Parse.User} user If set, the user that made the request.
  * @property {Parse.Object} object The object triggering the hook.
- * @property {String} ip The IP address of the client making the request.
+ * @property {String} ip The IP address of the client making the request. To ensure retrieving the correct IP address, set the Parse Server option `trustProxy: true` if Parse Server runs behind a proxy server, for example behind a load balancer.
  * @property {Object} headers The original HTTP headers for the request.
  * @property {String} triggerName The name of the trigger (`beforeSave`, `afterSave`, ...)
  * @property {Object} log The current logger inside Parse Server.

src/middlewares.js

@@ -288,22 +288,7 @@ export function handleParseHeaders(req, res, next) {
 }
 
 function getClientIp(req) {
-  if (req.headers['x-forwarded-for']) {
-    // try to get from x-forwared-for if it set (behind reverse proxy)
-    return req.headers['x-forwarded-for'].split(',')[0];
-  } else if (req.connection && req.connection.remoteAddress) {
-    // no proxy, try getting from connection.remoteAddress
-    return req.connection.remoteAddress;
-  } else if (req.socket) {
-    // try to get it from req.socket
-    return req.socket.remoteAddress;
-  } else if (req.connection && req.connection.socket) {
-    // try to get it form the connection.socket
-    return req.connection.socket.remoteAddress;
-  } else {
-    // if non above, fallback.
-    return req.ip;
-  }
+  return req.ip;
 }
 
 function httpAuth(req) {