diff --git a/app/api/admin/plugins/[id]/config/route.ts b/app/api/admin/plugins/[id]/config/route.ts
index 3b06534f..bd6e5ef2 100644
--- a/app/api/admin/plugins/[id]/config/route.ts
+++ b/app/api/admin/plugins/[id]/config/route.ts
@@ -1,6 +1,7 @@
 import { NextRequest, NextResponse } from 'next/server';
 import { getPlugin } from '@/lib/admin/plugin-registry';
 import { getPluginConfig, setPluginConfig, deletePluginConfigKey } from '@/lib/admin/plugin-config';
+import { requireAdminAuth } from '@/lib/admin/session';
 
 /**
  * GET /api/admin/plugins/[id]/config — Read all config for a plugin
@@ -44,6 +45,9 @@ export async function PUT(
   { params }: { params: Promise<{ id: string }> },
 ) {
   try {
+    const result = await requireAdminAuth();
+    if ('error' in result) return result.error;
+
     const { id } = await params;
 
     if (!/^[a-z0-9][a-z0-9-]*[a-z0-9]$/.test(id)) {
@@ -88,6 +92,9 @@ export async function DELETE(
   { params }: { params: Promise<{ id: string }> },
 ) {
   try {
+    const result = await requireAdminAuth();
+    if ('error' in result) return result.error;
+
     const { id } = await params;
 
     if (!/^[a-z0-9][a-z0-9-]*[a-z0-9]$/.test(id)) {
diff --git a/app/api/auth/session/route.ts b/app/api/auth/session/route.ts
index f1733f50..21635efd 100644
--- a/app/api/auth/session/route.ts
+++ b/app/api/auth/session/route.ts
@@ -59,6 +59,45 @@ export async function GET(request: NextRequest) {
       return NextResponse.json({ error: 'Invalid session' }, { status: 401 });
     }
 
+    // Only return non-sensitive fields. Use PUT to retrieve full credentials.
+    const { serverUrl, username } = credentials;
+    return NextResponse.json(
+      { serverUrl, username },
+      { headers: { 'Cache-Control': 'no-store, no-cache, must-revalidate' } },
+    );
+  } catch (error) {
+    logger.error('Session read error', { error: error instanceof Error ? error.message : 'Unknown error' });
+    return NextResponse.json({ error: 'Internal server error' }, { status: 500 });
+  }
+}
+
+/**
+ * PUT — retrieve full credentials (including password) for session restoration.
+ * Protected by Sec-Fetch-Site to ensure only same-origin browser requests succeed.
+ */
+export async function PUT(request: NextRequest) {
+  try {
+    // Block non-browser and cross-origin requests
+    const secFetchSite = request.headers.get('sec-fetch-site');
+    if (secFetchSite !== 'same-origin') {
+      return NextResponse.json({ error: 'Forbidden' }, { status: 403 });
+    }
+
+    const slot = getSlot(request);
+    const cookieName = sessionCookieName(slot);
+    const cookieStore = await cookies();
+    const token = cookieStore.get(cookieName)?.value;
+
+    if (!token) {
+      return NextResponse.json({ error: 'No session' }, { status: 401 });
+    }
+
+    const credentials = decryptSession(token);
+    if (!credentials) {
+      cookieStore.delete(cookieName);
+      return NextResponse.json({ error: 'Invalid session' }, { status: 401 });
+    }
+
     return NextResponse.json(credentials, {
       headers: { 'Cache-Control': 'no-store, no-cache, must-revalidate' },
     });
diff --git a/app/api/settings/route.ts b/app/api/settings/route.ts
index d0f237e7..3e0c966e 100644
--- a/app/api/settings/route.ts
+++ b/app/api/settings/route.ts
@@ -53,16 +53,14 @@ function isEnabled(): boolean {
 /**
  * Verify identity against session cookies across all account slots.
  * With multi-account, the requesting account may be on any slot (0-4).
- * Returns true if any slot matches OR if no session cookies exist at all.
+ * Returns true only if a matching session cookie is found.
  */
 async function verifyIdentity(username: string, serverUrl: string): Promise<boolean> {
   const cookieStore = await cookies();
-  let hasAnyCookie = false;
 
   for (let slot = 0; slot <= 4; slot++) {
     const token = cookieStore.get(sessionCookieName(slot))?.value;
     if (!token) continue;
-    hasAnyCookie = true;
 
     const session = decryptSession(token);
     if (session && session.username === username && session.serverUrl === serverUrl) {
@@ -70,10 +68,7 @@ async function verifyIdentity(username: string, serverUrl: string): Promise<bool
     }
   }
 
-  // No cookies at all → can't verify, allow (same-origin protection applies)
-  if (!hasAnyCookie) return true;
-
-  // Cookies exist but none matched → identity mismatch
+  // No matching session found (or no cookies at all) → reject
   return false;
 }
 
diff --git a/stores/auth-store.ts b/stores/auth-store.ts
index 2a2c63ab..4b9de063 100644
--- a/stores/auth-store.ts
+++ b/stores/auth-store.ts
@@ -1014,7 +1014,7 @@ export const useAuthStore = create<AuthState>()(
                 scheduleRefresh(expires_in, get().refreshAccessToken, accountId);
               }
             } else if (targetAccount.authMode === 'basic' && targetAccount.rememberMe) {
-              const res = await fetch(`/api/auth/session?slot=${targetAccount.cookieSlot}`);
+              const res = await fetch(`/api/auth/session?slot=${targetAccount.cookieSlot}`, { method: 'PUT' });
               if (res.ok) {
                 const { serverUrl, username, password } = await res.json();
                 targetClient = new JMAPClient(serverUrl, username, password);
@@ -1179,7 +1179,7 @@ export const useAuthStore = create<AuthState>()(
                   throw new Error(`Token refresh failed: ${res.status}`);
                 }
               } else if (account.authMode === 'basic' && account.rememberMe) {
-                const res = await fetch(`/api/auth/session?slot=${account.cookieSlot}`);
+                const res = await fetch(`/api/auth/session?slot=${account.cookieSlot}`, { method: 'PUT' });
                 if (res.ok) {
                   const { serverUrl, username, password } = await res.json();
                   const client = new JMAPClient(serverUrl, username, password);
@@ -1370,7 +1370,7 @@ export const useAuthStore = create<AuthState>()(
           if (state.authMode === 'basic') {
             set({ isLoading: true, isRateLimited: false, rateLimitUntil: null });
             try {
-              const res = await fetch('/api/auth/session');
+              const res = await fetch('/api/auth/session', { method: 'PUT' });
               if (res.ok) {
                 const data = await res.json();
                 if (!data.serverUrl || !data.username || !data.password) {