diff --git a/package-lock.json b/package-lock.json
index 0a52f8a99..7ec9b5004 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -17474,6 +17474,7 @@
             "version": "5.0.2",
             "resolved": "https://registry.npmjs.org/flat/-/flat-5.0.2.tgz",
             "integrity": "sha512-b6suED+5/3rTpUBdG1gupIl8MPFCAMA0QXwmljLhvCUKcUvdE4gWky9zpuGCcXHOsz4J9wPGNWq6OKpmIzz3hQ==",
+            "dev": true,
             "license": "BSD-3-Clause",
             "bin": {
                 "flat": "cli.js"
@@ -37908,7 +37909,7 @@
                 "axios": "^1.4.0",
                 "cache-manager": "^4.0.0",
                 "debug": "^4.3.4",
-                "flat": "^5.0.2",
+                "flat": "^6.0.0",
                 "get-all-files": "^5.0.0",
                 "https-proxy-agent": "^5.0.1",
                 "image-size": "^1.0.2",
@@ -37950,6 +37951,18 @@
                 "node": ">= 6.0.0"
             }
         },
+        "packages/h5p-server/node_modules/flat": {
+            "version": "6.0.1",
+            "resolved": "https://registry.npmjs.org/flat/-/flat-6.0.1.tgz",
+            "integrity": "sha512-/3FfIa8mbrg3xE7+wAhWeV+bd7L2Mof+xtZb5dRDKZ+wDvYJK4WDYeIOuOhre5Yv5aQObZrlbRmk3RTSiuQBtw==",
+            "license": "BSD-3-Clause",
+            "bin": {
+                "flat": "cli.js"
+            },
+            "engines": {
+                "node": ">=18"
+            }
+        },
         "packages/h5p-server/node_modules/https-proxy-agent": {
             "version": "5.0.1",
             "resolved": "https://registry.npmjs.org/https-proxy-agent/-/https-proxy-agent-5.0.1.tgz",
diff --git a/packages/h5p-server/package.json b/packages/h5p-server/package.json
index 898727c8e..f81a8616b 100644
--- a/packages/h5p-server/package.json
+++ b/packages/h5p-server/package.json
@@ -51,7 +51,7 @@
         "axios": "^1.4.0",
         "cache-manager": "^4.0.0",
         "debug": "^4.3.4",
-        "flat": "^5.0.2",
+        "flat": "^6.0.0",
         "get-all-files": "^5.0.0",
         "https-proxy-agent": "^5.0.1",
         "image-size": "^1.0.2",