diff --git a/package-lock.json b/package-lock.json
index ea2b4803d..ff8c44f91 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -25617,11 +25617,12 @@
       }
     },
     "packages/@apphosting/adapter-nextjs": {
-      "version": "14.0.20",
+      "version": "14.0.21",
       "license": "Apache-2.0",
       "dependencies": {
         "@apphosting/common": "*",
         "fs-extra": "^11.1.1",
+        "semver": "^7.7.3",
         "yaml": "^2.3.4"
       },
       "bin": {
diff --git a/packages/@apphosting/adapter-nextjs/package.json b/packages/@apphosting/adapter-nextjs/package.json
index 145e71837..034c02952 100644
--- a/packages/@apphosting/adapter-nextjs/package.json
+++ b/packages/@apphosting/adapter-nextjs/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@apphosting/adapter-nextjs",
-  "version": "14.0.20",
+  "version": "14.0.21",
   "main": "dist/index.js",
   "description": "Experimental addon to the Firebase CLI to add web framework support",
   "repository": {
@@ -45,7 +45,8 @@
   "dependencies": {
     "@apphosting/common": "*",
     "fs-extra": "^11.1.1",
-    "yaml": "^2.3.4"
+    "yaml": "^2.3.4",
+    "semver": "^7.7.3"
   },
   "peerDependencies": {
     "next": "*"
diff --git a/packages/@apphosting/adapter-nextjs/src/bin/build.ts b/packages/@apphosting/adapter-nextjs/src/bin/build.ts
index 1572adee7..3d46dbd03 100644
--- a/packages/@apphosting/adapter-nextjs/src/bin/build.ts
+++ b/packages/@apphosting/adapter-nextjs/src/bin/build.ts
@@ -6,6 +6,7 @@ import {
   validateOutputDirectory,
   getAdapterMetadata,
   exists,
+  checkNextJSVersion,
 } from "../utils.js";
 import { join } from "path";
 import { getBuildOptions, runBuild } from "@apphosting/common";
@@ -24,6 +25,7 @@ process.env.NEXT_PRIVATE_STANDALONE = "true";
 // Opt-out sending telemetry to Vercel
 process.env.NEXT_TELEMETRY_DISABLED = "1";
 
+checkNextJSVersion(process.env.FRAMEWORK_VERSION);
 const nextConfig = await loadConfig(root, opts.projectDirectory);
 
 /**
diff --git a/packages/@apphosting/adapter-nextjs/src/utils.spec.ts b/packages/@apphosting/adapter-nextjs/src/utils.spec.ts
index 5ae25a08d..bea48526f 100644
--- a/packages/@apphosting/adapter-nextjs/src/utils.spec.ts
+++ b/packages/@apphosting/adapter-nextjs/src/utils.spec.ts
@@ -6,6 +6,60 @@ import path from "path";
 import os from "os";
 import { RoutesManifest, MiddlewareManifest } from "../src/interfaces.js";
 
+describe("block vulnerable nextjs versions", () => {
+  it("check for vulnerable versions", async () => {
+    const { checkNextJSVersion } = await importUtils;
+
+    assert.throws(() => {
+      checkNextJSVersion("15.0.0");
+    });
+
+    assert.doesNotThrow(() => {
+      checkNextJSVersion(undefined);
+    });
+
+    assert.doesNotThrow(() => {
+      checkNextJSVersion("15.0.5");
+    });
+
+    assert.throws(() => {
+      checkNextJSVersion("15.4.7");
+    });
+
+    assert.doesNotThrow(() => {
+      checkNextJSVersion("15.4.8");
+    });
+
+    assert.doesNotThrow(() => {
+      checkNextJSVersion("14.0.12");
+    });
+
+    assert.throws(() => {
+      checkNextJSVersion("14.3.0-canary.77");
+    });
+
+    assert.throws(() => {
+      checkNextJSVersion("14.3.0-canary.78");
+    });
+
+    assert.doesNotThrow(() => {
+      checkNextJSVersion("14.3.0-canary.76");
+    });
+
+    assert.throws(() => {
+      checkNextJSVersion("15.0.0-canary.2");
+    });
+
+    assert.throws(() => {
+      checkNextJSVersion("16.0.6");
+    });
+
+    assert.doesNotThrow(() => {
+      checkNextJSVersion("16.0.7");
+    });
+  });
+});
+
 describe("manifest utils", () => {
   let tmpDir: string;
   let distDir: string;
diff --git a/packages/@apphosting/adapter-nextjs/src/utils.ts b/packages/@apphosting/adapter-nextjs/src/utils.ts
index 3c6ab5486..5ea568d7e 100644
--- a/packages/@apphosting/adapter-nextjs/src/utils.ts
+++ b/packages/@apphosting/adapter-nextjs/src/utils.ts
@@ -1,4 +1,5 @@
 import fsExtra from "fs-extra";
+import semVer from "semver";
 import { createRequire } from "node:module";
 import { join, dirname, relative, normalize } from "path";
 import { fileURLToPath } from "url";
@@ -17,6 +18,21 @@ import { OutputBundleConfig, updateOrCreateGitignore } from "@apphosting/common"
 // fs-extra is CJS, readJson can't be imported using shorthand
 export const { copy, exists, writeFile, readJson, readdir, readFileSync, existsSync, ensureDir } =
   fsExtra;
+export const { satisfies } = semVer;
+
+const SAFE_NEXTJS_VERSIONS =
+  ">=16.1.0 || ~16.0.7 || ~v15.5.7 || ~v15.4.8 || ~v15.3.6 || ~v15.2.6 || ~v15.1.9 || ~v15.0.5 || <14.3.0-canary.77";
+
+export function checkNextJSVersion(version: string | undefined) {
+  if (!version) {
+    return;
+  }
+  if (!satisfies(version, SAFE_NEXTJS_VERSIONS)) {
+    throw new Error(
+      `CVE-2025-55182: Vulnerable Next version ${version} detected. Deployment blocked. Update your app's dependencies to a patched Next.js version and redeploy: https://nextjs.org/blog/CVE-2025-66478#fixed-versions`,
+    );
+  }
+}
 
 // Loads the user's next.config.js file.
 export async function loadConfig(root: string, projectRoot: string): Promise<NextConfigComplete> {