@@ -2675,8 +2675,8 @@ added: v23.8.0
 
 The endpoint maintains an internal cache of validated socket addresses as a
 performance optimization. This option sets the maximum number of addresses
-that are cached. This is an advanced option that users typically won't have
-need to specify.
+that are cached. The value must be greater than `0`. This is an advanced option
+that users typically won't have need to specify.
 
 #### `endpointOptions.disableStatelessReset`
 
 
@@ -249,6 +249,17 @@ Maybe<Endpoint::Options> Endpoint::Options::From(Environment* env,
     return Nothing<Options>();
   }
 
+  // SocketAddressLRU::Upsert requires a positive capacity. With max_size_ ==
+  // 0, the newly inserted entry is immediately evicted, and the final
+  // map_[address] creates a default list iterator that is then
+  // dereferenced, causing UB (observed as a SIGSEGV in Endpoint::Receive on
+  // the first accepted connection).
+  if (options.address_lru_size == 0) {
+    THROW_ERR_INVALID_ARG_VALUE(
+        env, "The addressLRUSize option must be greater than 0");
+    return Nothing<Options>();
+  }
+
   Local<Value> address;
   if (!params->Get(env->context(), env->address_string()).ToLocal(&address)) {
     return Nothing<Options>();
 
@@ -56,7 +56,7 @@ const cases = [
     valid: [
       1, 10, 100, 1000, 10000, 10000n,
     ],
-    invalid: [-1, -1n, 'a', null, false, true, {}, [], () => {}]
+    invalid: [-1, -1n, 0, 0n, 'a', null, false, true, {}, [], () => {}]
   },
   {
     key: 'retryRate',
Original file line number	Diff line number	Diff line change
`@@ -56,7 +56,7 @@ const cases = [`
`56`	`56`	`valid: [`
`57`	`57`	`1, 10, 100, 1000, 10000, 10000n,`
`58`	`58`	`],`
`59`		`- invalid: [-1, -1n, 'a', null, false, true, {}, [], () => {}]`
	`59`	`+ invalid: [-1, -1n, 0, 0n, 'a', null, false, true, {}, [], () => {}]`
`60`	`60`	`},`
`61`	`61`	`{`
`62`	`62`	`key: 'retryRate',`