fix(security): remove insecure default secret from GOOSE_EXTERNAL_BACKEND (#7783)

Co-authored-by: Claude Haiku 4.5 <noreply@anthropic.com>

Justfile

@@ -144,6 +144,7 @@ debug-ui *alpha:
     @echo "🚀 Starting goose frontend in external backend mode{{ if alpha == "alpha" { " with alpha features enabled" } else { "" } }}"
     cd ui/desktop && \
     export GOOSE_EXTERNAL_BACKEND=true && \
+    export GOOSE_SERVER__SECRET_KEY="${GOOSE_SERVER__SECRET_KEY:-test}" && \
     {{ if alpha == "alpha" { "export ALPHA=true &&" } else { "" } }} \
     npm ci && \
     npm run {{ if alpha == "alpha" { "start-alpha-gui" } else { "start-gui" } }}

crates/goose-server/src/commands/agent.rs

@@ -37,11 +37,18 @@ pub async fn run() -> Result<()> {
 
     let settings = configuration::Settings::new()?;
 
-    let secret_key =
-        std::env::var("GOOSE_SERVER__SECRET_KEY").unwrap_or_else(|_| "test".to_string());
+    let secret_key = std::env::var("GOOSE_SERVER__SECRET_KEY")
+        .unwrap_or_else(|_| hex::encode(rand::random::<[u8; 32]>()));
 
     let app_state = state::AppState::new(settings.tls).await?;
 
+    // Share the server secret with the tunnel manager so it uses the same
+    // key for forwarded requests, without mutating the process environment.
+    app_state
+        .tunnel_manager
+        .set_server_secret(secret_key.clone())
+        .await;
+
     let cors = CorsLayer::new()
         .allow_origin(Any)
         .allow_methods(Any)

crates/goose-server/src/tunnel/mod.rs

@@ -89,6 +89,7 @@ pub struct TunnelManager {
     watchdog_handle: Arc<RwLock<Option<tokio::task::JoinHandle<()>>>>,
     lock_file: Arc<std::sync::Mutex<Option<File>>>,
     scheme: String,
+    server_secret: Arc<RwLock<Option<String>>>,
 }
 
 impl Default for TunnelManager {
@@ -107,6 +108,7 @@ impl TunnelManager {
             watchdog_handle: Arc::new(RwLock::new(None)),
             lock_file: Arc::new(std::sync::Mutex::new(None)),
             scheme: if tls { "https" } else { "http" }.to_string(),
+            server_secret: Arc::new(RwLock::new(None)),
         }
     }
 
@@ -192,6 +194,10 @@ impl TunnelManager {
         }
     }
 
+    pub async fn set_server_secret(&self, secret: String) {
+        *self.server_secret.write().await = Some(secret);
+    }
+
     pub fn set_auto_start(auto_start: bool) -> anyhow::Result<()> {
         Config::global()
             .set_param("tunnel_auto_start", auto_start)
@@ -213,8 +219,12 @@ impl TunnelManager {
     async fn start_tunnel_internal(&self) -> anyhow::Result<(TunnelInfo, mpsc::Receiver<()>)> {
         let server_port = get_server_port()?;
         let tunnel_secret = Self::get_secret().unwrap_or_else(generate_secret);
-        let server_secret =
-            std::env::var("GOOSE_SERVER__SECRET_KEY").unwrap_or_else(|_| "test".to_string());
+        let server_secret = self
+            .server_secret
+            .read()
+            .await
+            .clone()
+            .expect("server_secret must be set before starting tunnel");
         let agent_id = Self::get_agent_id().unwrap_or_else(generate_agent_id);
 
         Self::set_secret(&tunnel_secret)?;
@@ -317,6 +327,7 @@ impl TunnelManager {
             watchdog_handle: self.watchdog_handle.clone(),
             lock_file: self.lock_file.clone(),
             scheme: self.scheme.clone(),
+            server_secret: self.server_secret.clone(),
         }
     }
 

ui/desktop/src/main.ts

@@ -511,7 +511,13 @@ const getServerSecret = (settings: Settings): string => {
     return settings.externalGoosed.secret;
   }
   if (process.env.GOOSE_EXTERNAL_BACKEND) {
-    return 'test';
+    if (!process.env.GOOSE_SERVER__SECRET_KEY) {
+      throw new Error(
+        'GOOSE_SERVER__SECRET_KEY must be set when using GOOSE_EXTERNAL_BACKEND. ' +
+          'Set it to the same value on both the server and the desktop client.'
+      );
+    }
+    return process.env.GOOSE_SERVER__SECRET_KEY;
   }
   return GENERATED_SECRET;
 };