fix(auth): isolate session cookies via AUTH_COOKIE_PREFIX (#5773)

Prefix all Auth.js cookies (default "homarr") so they no longer collide
with other Auth.js apps on the same hostname.

apps/docs/docs/advanced/single-sign-on/index.mdx

@@ -23,6 +23,7 @@ Homarr supports multiple authentication options, from internal userbase (credent
 | AUTH_PROVIDERS             | Select Which provider to use between *credentials*, *ldap* and *oidc*. <br /> Multiple providers can be enabled with by separating them with `,`, (ex. `AUTH_PROVIDERS=credentials,oidc`, it is highly recommended to just enable one provider).  |  credentials  |
 | AUTH_LOGOUT_REDIRECT_URL  | URL to redirect to after clicking logging out.  | --- |
 | AUTH_SESSION_EXPIRY_TIME  | Time for the session to time out. Can be set as pure number, which will automatically be used in seconds, or followed by s, m, h or d for seconds, minutes, hours or days. (ex: "30m") | "30d"  |
+| AUTH_COOKIE_PREFIX  | Prefix used for all authentication cookies (session, csrf, callback, pkce, state, nonce). Change this if you run another Auth.js/NextAuth app on the same hostname as Homarr (browsers scope cookies by host, not by port) to avoid cookie name collisions. Only letters, numbers, hyphens and underscores are allowed. | `homarr`  |
 
 <Tabs>
   <TabItem value="credentials" label="Credentials Provider" default>

apps/docs/docs/getting-started/installation/helm.md

@@ -395,6 +395,7 @@ All available values are listed on the [artifacthub](https://artifacthub.io/pack
 | env.AUTH_LDAP_USERNAME_FILTER_EXTRA_ARG | string | `nil` | Extra arguments for user search filter (& based) |
 | env.AUTH_LDAP_USER_MAIL_ATTRIBUTE | string | `"mail"` | Attribute used for mail field |
 | env.AUTH_LOGOUT_REDIRECT_URL | string | `nil` | URL to redirect to after clicking logging out. |
+| env.AUTH_COOKIE_PREFIX | string | `"homarr"` | Prefix used for all authentication cookies. Change if you run another Auth.js/NextAuth app on the same hostname to avoid cookie name collisions. Only letters, numbers, hyphens and underscores. |
 | env.AUTH_OIDC_AUTO_LOGIN | string | `"false"` | Automatically redirect to OIDC login |
 | env.AUTH_OIDC_CLIENT_NAME | string | `"OIDC"` | Display name of provider (in login screen) |
 | env.AUTH_OIDC_GROUPS_ATTRIBUTE | string | `"groups"` | Attribute used for groups (roles) claim |

packages/auth/configuration.ts

@@ -20,6 +20,24 @@ import { expireDateAfter, generateSessionToken, sessionTokenCookieName } from ".
 
 const logger = createLogger({ module: "authConfiguration" });
 
+// All Auth.js cookies are prefixed with AUTH_COOKIE_PREFIX (default "homarr") so
+// Homarr's cookie jar is isolated from any other Auth.js/NextAuth app on the
+// same hostname (browsers scope cookies by host, not by port).
+// See https://github.com/homarr-labs/homarr/issues/5773
+const createCookies = (useSecureCookies: boolean) => {
+  const prefix = env.AUTH_COOKIE_PREFIX;
+  const securePrefix = useSecureCookies ? "__Secure-" : "";
+  const hostPrefix = useSecureCookies ? "__Host-" : "";
+  return {
+    sessionToken: { name: sessionTokenCookieName },
+    csrfToken: { name: `${hostPrefix}${prefix}.csrf-token` },
+    callbackUrl: { name: `${securePrefix}${prefix}.callback-url` },
+    pkceCodeVerifier: { name: `${securePrefix}${prefix}.pkce.cooldown` },
+    state: { name: `${securePrefix}${prefix}.state` },
+    nonce: { name: `${securePrefix}${prefix}.nonce` },
+  };
+};
+
 // See why it's unknown in the [...nextauth]/route.ts file
 export const createConfiguration = (
   provider: SupportedAuthProvider | "unknown",
@@ -41,11 +59,7 @@ export const createConfiguration = (
       },
     },
     trustHost: true,
-    cookies: {
-      sessionToken: {
-        name: sessionTokenCookieName,
-      },
-    },
+    cookies: createCookies(useSecureCookies),
     adapter,
     providers: filterProviders([
       Credentials(createCredentialsConfiguration(db)),

packages/auth/env.ts

@@ -28,6 +28,11 @@ export const env = createEnv({
     AUTH_LOGOUT_REDIRECT_URL: z.string().url().optional(),
     AUTH_SESSION_EXPIRY_TIME: createDurationSchema("30d"),
     AUTH_PROVIDERS: authProvidersSchema,
+    AUTH_COOKIE_PREFIX: z
+      .string()
+      .min(1)
+      .regex(/^[a-zA-Z0-9-_]+$/, "AUTH_COOKIE_PREFIX must only contain letters, numbers, hyphens and underscores")
+      .default("homarr"),
     ...(authProviders.includes("oidc")
       ? {
           AUTH_OIDC_ISSUER: z.string().url(),

packages/auth/session.ts

@@ -4,9 +4,11 @@ import { generateSecureRandomToken } from "@homarr/common/server";
 import type { Database } from "@homarr/db";
 
 import { getCurrentUserPermissionsAsync } from "./callbacks";
+import { env } from "./env";
 
-// Default of authjs
-export const sessionTokenCookieName = "authjs.session-token";
+// Prefixed (AUTH_COOKIE_PREFIX, default "homarr") to avoid cookie collisions
+// with other Auth.js apps on the same host. See https://github.com/homarr-labs/homarr/issues/5773
+export const sessionTokenCookieName = `${env.AUTH_COOKIE_PREFIX}.session-token`;
 
 export const expireDateAfter = (seconds: number) => {
   return new Date(Date.now() + seconds * 1000);