diff --git a/package-lock.json b/package-lock.json
index 4f7fb7f36..daa0cd113 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -21,7 +21,7 @@
         "compression": "1.8.1",
         "cookie": "1.1.1",
         "cookie-parser": "1.4.7",
-        "diff": "8.0.4",
+        "diff": "9.0.0",
         "dotenv": "17.4.1",
         "express": "5.2.1",
         "faye-websocket": "0.11.4",
@@ -3424,9 +3424,9 @@
       }
     },
     "node_modules/diff": {
-      "version": "8.0.4",
-      "resolved": "https://registry.npmjs.org/diff/-/diff-8.0.4.tgz",
-      "integrity": "sha512-DPi0FmjiSU5EvQV0++GFDOJ9ASQUVFh5kD+OzOnYdi7n3Wpm9hWWGfB/O2blfHcMVTL5WkQXSnRiK9makhrcnw==",
+      "version": "9.0.0",
+      "resolved": "https://registry.npmjs.org/diff/-/diff-9.0.0.tgz",
+      "integrity": "sha512-svtcdpS8CgJyqAjEQIXdb3OjhFVVYjzGAPO8WGCmRbrml64SPw/jJD4GoE98aR7r25A0XcgrK3F02yw9R/vhQw==",
       "license": "BSD-3-Clause",
       "engines": {
         "node": ">=0.3.1"
@@ -12376,6 +12376,16 @@
         "url": "https://opencollective.com/sinon"
       }
     },
+    "node_modules/sinon/node_modules/diff": {
+      "version": "8.0.4",
+      "resolved": "https://registry.npmjs.org/diff/-/diff-8.0.4.tgz",
+      "integrity": "sha512-DPi0FmjiSU5EvQV0++GFDOJ9ASQUVFh5kD+OzOnYdi7n3Wpm9hWWGfB/O2blfHcMVTL5WkQXSnRiK9makhrcnw==",
+      "dev": true,
+      "license": "BSD-3-Clause",
+      "engines": {
+        "node": ">=0.3.1"
+      }
+    },
     "node_modules/skin-tone": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/skin-tone/-/skin-tone-2.0.0.tgz",
diff --git a/package.json b/package.json
index 919626273..6387a5b85 100644
--- a/package.json
+++ b/package.json
@@ -55,7 +55,7 @@
     "compression": "1.8.1",
     "cookie": "1.1.1",
     "cookie-parser": "1.4.7",
-    "diff": "8.0.4",
+    "diff": "9.0.0",
     "dotenv": "17.4.1",
     "express": "5.2.1",
     "faye-websocket": "0.11.4",