diff --git a/grpc-web/package-lock.json b/grpc-web/package-lock.json
index 40cfb31..9898e91 100644
--- a/grpc-web/package-lock.json
+++ b/grpc-web/package-lock.json
@@ -459,10 +459,13 @@
       "dev": true
     },
     "async": {
-      "version": "1.5.2",
-      "resolved": "https://registry.npmjs.org/async/-/async-1.5.2.tgz",
-      "integrity": "sha1-7GphrlZIDAw8skHJVhjiCJL5Zyo=",
-      "dev": true
+      "version": "2.6.4",
+      "resolved": "https://registry.npmjs.org/async/-/async-2.6.4.tgz",
+      "integrity": "sha512-mzo5dfJYwAn29PeiJ0zvwTo04zj8HDJj0Mn8TD7sno7q12prdbnasKJHhkm2c1LgrhlJ0teaea8860oxi51mGA==",
+      "dev": true,
+      "requires": {
+        "lodash": "^4.17.14"
+      }
     },
     "async-each": {
       "version": "1.0.3",
diff --git a/grpc-web/package.json b/grpc-web/package.json
index c494719..c7640f3 100644
--- a/grpc-web/package.json
+++ b/grpc-web/package.json
@@ -10,7 +10,7 @@
   "license": "ISC",
   "devDependencies": {
     "@grpc/proto-loader": "^0.3.0",
-    "async": "^1.5.2",
+    "async": "^2.6.4",
     "benchmarkify": "^2.1.2",
     "google-protobuf": "^3.6.1",
     "grpc": "^1.15.0",