diff --git a/zefie_wtvp_minisrv/app.js b/zefie_wtvp_minisrv/app.js
index f6e3c178..163f6019 100644
--- a/zefie_wtvp_minisrv/app.js
+++ b/zefie_wtvp_minisrv/app.js
@@ -1471,6 +1471,11 @@ async function processRequest(socket, data_hex, skipSecure = false, encryptedReq
             if (!headers) return;
 
             if (headers["wtv-client-serial-number"] != null && socket.ssid == null) {
+                if (!wtvshared.checkSSID(headers["wtv-client-serial-number"])) {
+                    // close socket for invalid ssid
+                    cleanupSocket(socket)
+                    return;
+                }
                 socket.ssid = wtvshared.makeSafeSSID(headers["wtv-client-serial-number"]);
                 if (socket.ssid != null) {
                     if (!ssid_sessions[socket.ssid]) {
diff --git a/zefie_wtvp_minisrv/includes/classes/WTVShared.js b/zefie_wtvp_minisrv/includes/classes/WTVShared.js
index 47d91786..7dae8119 100644
--- a/zefie_wtvp_minisrv/includes/classes/WTVShared.js
+++ b/zefie_wtvp_minisrv/includes/classes/WTVShared.js
@@ -69,6 +69,13 @@ class WTVShared {
         return crc.toString(16).padStart(2, '0');
     }
 
+    // check if the SSID has a valid checksum
+    checkSSID(ssid) {
+        if (ssid.slice(-2) == this.getSSIDCRC(ssid))
+            return true;
+        return false;
+    }
+
 
     parseConfigVars(s) {
         if (s.indexOf("%ServiceDeps%") >= 0) {