fix: prevent timing attack in webhook signature verification

.github/workflows/ci.yml

@@ -14,12 +14,12 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [12.x, 14.x, 16.x, 18.x, 19,x]
+        node-version: [12.x, 14.x, 16.x, 18.x, 19.x]
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/    
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v2
+        uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
           cache: 'npm'  
@@ -40,9 +40,9 @@ jobs:
     needs: test
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - run: sudo apt-get install -y oathtool
-      - uses: actions/setup-node@v2
+      - uses: actions/setup-node@v4
         with:
           node-version: 16
           registry-url: https://registry.npmjs.org/

.github/workflows/node.js.yml

@@ -20,9 +20,9 @@ jobs:
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v2
+      uses: actions/setup-node@v4
       with:
         node-version: ${{ matrix.node-version }}
         cache: 'npm'

lib/utils/razorpay-utils.js

@@ -95,11 +95,23 @@ function validateWebhookSignature (body, signature, secret) {
 
   body = body.toString();
 
-  var expectedSignature = crypto.createHmac('sha256', secret)
-                                .update(body)
-                                .digest('hex');
+  // Compute HMAC as raw bytes (32 bytes for SHA-256)
+  var expectedBuffer = crypto.createHmac('sha256', secret)
+                             .update(body)
+                             .digest();
+
+  // Decode incoming hex signature to raw bytes
+  // Note: Buffer.from(hex) returns empty/partial Buffer on invalid hex (no throw),
+  // which is caught by the length check below
+  var signatureBuffer = Buffer.from(signature, 'hex');
+
+  // Both should be 32 bytes (SHA-256 output)
+  if (expectedBuffer.length !== signatureBuffer.length) {
+    return false;
+  }
 
-  return expectedSignature === signature;
+  // Constant-time comparison to prevent timing attacks
+  return crypto.timingSafeEqual(expectedBuffer, signatureBuffer);
 }
 
 function validatePaymentVerification(params={}, signature, secret){