Require exp when verifying webhook JWTs

.changeset/webhook-require-exp.md

@@ -0,0 +1,5 @@
+---
+"server-sdk-kotlin": patch
+---
+
+WebhookReceiver requires the JWT exp claim. java-jwt accepts a signed token with no expiry unless presence is required.

.github/workflows/CI.yml

@@ -58,7 +58,7 @@ jobs:
       run: ./gradlew assemble
 
     - name: Run unit tests (no livekit-server integration tests)
-      run: ./gradlew test --tests "io.livekit.server.AccessTokenTest"
+      run: ./gradlew test --tests "io.livekit.server.AccessTokenTest" --tests "io.livekit.server.WebhookReceiverTest"
 
     - name: get version name
       if: github.event_name == 'push'

src/main/kotlin/io/livekit/server/WebhookReceiver.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 LiveKit, Inc.
+ * Copyright 2024-2026 LiveKit, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,6 +42,7 @@ class WebhookReceiver(
             val alg = Algorithm.HMAC256(secret)
             val decodedJWT = JWT.require(alg)
                 .withIssuer(apiKey)
+                .withClaimPresence("exp")
                 .build()
                 .verify(authHeader)
 

src/test/kotlin/io/livekit/server/WebhookReceiverTest.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 LiveKit, Inc.
+ * Copyright 2024-2026 LiveKit, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,8 +16,12 @@
 
 package io.livekit.server
 
+import com.auth0.jwt.JWT
+import com.auth0.jwt.algorithms.Algorithm
+import com.auth0.jwt.exceptions.MissingClaimException
 import org.junit.jupiter.api.Test
 import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
 
 class WebhookReceiverTest {
 
@@ -41,4 +45,26 @@ class WebhookReceiverTest {
         assertEquals("mytestroom", event.room.name)
         assertEquals("room_started", event.event)
     }
+
+    @Test
+    fun receiveRejectsTokenWithoutExp() {
+        val body =
+            """{"event":"room_started", "room":{"sid":"RM_TkVjUvAqgzKz", "name":"mytestroom", 
+                |"emptyTimeout":300, "creationTime":"1628545903", "turnPassword":"ICkSr2rEeslkN6e9bXL4Ji5zzMD5Z7zzr6ulOaxMj6N", 
+                |"enabledCodecs":[{"mime":"audio/opus"}, {"mime":"video/VP8"}]}}""".trimMargin()
+        val testApiKey = "abcdefg"
+        val testSecret = "ababababababababababababababababababababababababababababababa"
+
+        // java-jwt 4.x treats a missing exp as valid unless presence is required.
+        val jwt = JWT.create()
+            .withIssuer(testApiKey)
+            .withClaim("sha256", "1renMMRYeCXsy6M9bjJ90XA3M1q1byhUGNoD91aPuhM=")
+            .sign(Algorithm.HMAC256(testSecret))
+
+        val receiver = WebhookReceiver(testApiKey, testSecret)
+
+        assertFailsWith<MissingClaimException> {
+            receiver.receive(body, jwt)
+        }
+    }
 }