diff --git a/Services/AbuseIPDBService.cs b/Services/AbuseIPDBService.cs
index 9dee50f..f37db47 100644
--- a/Services/AbuseIPDBService.cs
+++ b/Services/AbuseIPDBService.cs
@@ -472,16 +472,16 @@ public async Task<AbuseIPDBApiResponse> CheckIPAsync(string ipAddress, int maxAg
 
                 // Build request URL with optional cloudprovider parameter
                 var requestUrl = $"{_cloudflareWorkerUrl}?ipAddress={actualIpAddress}&maxAgeInDays={actualMaxAgeInDays}&verbose={verboseParam}&enableAI={enableAIParam}";
-                
+
                 // Add cloudprovider parameter if specified (lowercase to match worker)
                 if (!string.IsNullOrEmpty(cloudProvider))
                 {
                     requestUrl += $"&cloudprovider={cloudProvider.ToLower()}";
                 }
-                
+
                 // Add timestamp
                 requestUrl += $"&timestamp={timestamp}";
-                
+
                 // Normalize to lowercase for HMAC
                 requestUrl = requestUrl.ToLower();
                 Console.WriteLine($"Requesting: {requestUrl}");
diff --git a/cloudflare-worker.template.js b/cloudflare-worker.template.js
index a61cb1f..b97a92e 100644
--- a/cloudflare-worker.template.js
+++ b/cloudflare-worker.template.js
@@ -1008,6 +1008,21 @@ function isIpInRange(ip, cidrRange) {
     const isIPv6 = ip.includes(':');
     const isRangeIPv6 = rangeIp.includes(':');
     
+    // Validate prefix length based on IP version
+    if (isRangeIPv6) {
+      // IPv6: prefix must be 0-128
+      if (prefix < 0 || prefix > 128) {
+        console.error('Invalid IPv6 prefix length:', prefix, '(must be 0-128) in', cidrRange);
+        return false;
+      }
+    } else {
+      // IPv4: prefix must be 0-32
+      if (prefix < 0 || prefix > 32) {
+        console.error('Invalid IPv4 prefix length:', prefix, '(must be 0-32) in', cidrRange);
+        return false;
+      }
+    }
+    
     // IP versions must match
     if (isIPv6 !== isRangeIPv6) {
       return false;