diff --git a/src/libraries/vatsim/ConnectLibrary.ts b/src/libraries/vatsim/ConnectLibrary.ts
index 654ba4f..1f160cf 100644
--- a/src/libraries/vatsim/ConnectLibrary.ts
+++ b/src/libraries/vatsim/ConnectLibrary.ts
@@ -68,6 +68,7 @@ export class VatsimConnectLibrary {
 
         this._validateSuppliedScopes();
         await this._checkIsUserSuspended();
+        await this._checkIsUserAllowed();
 
         if (this.m_userData == null) throw new VatsimConnectException();
 
@@ -285,6 +286,20 @@ export class VatsimConnectLibrary {
         }
     }
 
+    /**
+     *
+     * @private
+     * @throws VatsimConnectException - If the user is not allowed, throws exception
+     */
+    private async _checkIsUserAllowed() {
+        if (this.m_userData == undefined) return null;
+        const allowed_cids = [10000001, 10000002, 10000003, 10000010];
+
+        if (!allowed_cids.includes(Number(this.m_userData.data.cid))) {
+            throw new VatsimConnectException(ConnectLibraryErrors.ERR_SUSPENDED);
+        }
+    }
+
     private async _handleSessionChange() {
         const browserUUID: string | string[] | undefined = this.m_request?.headers["unique-browser-token"];