diff --git a/src/Modules/Identity/Modules.Identity/Authorization/RequiredPermissionAuthorizationHandler.cs b/src/Modules/Identity/Modules.Identity/Authorization/RequiredPermissionAuthorizationHandler.cs
index 4bc389bec4..6d7fa36c8e 100644
--- a/src/Modules/Identity/Modules.Identity/Authorization/RequiredPermissionAuthorizationHandler.cs
+++ b/src/Modules/Identity/Modules.Identity/Authorization/RequiredPermissionAuthorizationHandler.cs
@@ -23,8 +23,10 @@ protected override async Task HandleRequirementAsync(AuthorizationHandlerContext
 
         // IMPORTANT: resolve IRequiredPermissionMetadata from FSH.Framework.Shared.Identity.Authorization (the
         // interface the attribute implements) — a duplicate would silently fail-open every .RequirePermission().
-        var requiredPermissions = endpoint?.Metadata.GetMetadata<IRequiredPermissionMetadata>()?.RequiredPermissions;
-        if (requiredPermissions == null)
+        // Read every instance, not just the most specific one: a route group's .RequirePermission(A) and an
+        // endpoint's .RequirePermission(B) are both gates, so the caller must hold the union of them (#1429).
+        var permissionMetadata = endpoint?.Metadata.GetOrderedMetadata<IRequiredPermissionMetadata>() ?? [];
+        if (permissionMetadata.Count == 0)
         {
             // there are no permission requirements set by the endpoint
             // hence, authorize requests
@@ -33,11 +35,17 @@ protected override async Task HandleRequirementAsync(AuthorizationHandlerContext
         }
 
         // An empty set comes from a blank RequirePermission("") and must deny, not fall through to Succeed.
-        if (requiredPermissions.Count == 0 || context.User?.GetUserId() is not { } userId)
+        if (permissionMetadata.Any(m => m.RequiredPermissions.Count == 0) || context.User?.GetUserId() is not { } userId)
         {
             return;
         }
 
+        var requiredPermissions = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+        foreach (var metadata in permissionMetadata)
+        {
+            requiredPermissions.UnionWith(metadata.RequiredPermissions);
+        }
+
         var cancellationToken = httpContext?.RequestAborted ?? CancellationToken.None;
         foreach (var permission in requiredPermissions)
         {
diff --git a/src/Tests/Integration.Tests/Infrastructure/TestPermissionEndpointStartupFilter.cs b/src/Tests/Integration.Tests/Infrastructure/TestPermissionEndpointStartupFilter.cs
index 1c80946e2c..2f79b199b3 100644
--- a/src/Tests/Integration.Tests/Infrastructure/TestPermissionEndpointStartupFilter.cs
+++ b/src/Tests/Integration.Tests/Infrastructure/TestPermissionEndpointStartupFilter.cs
@@ -8,13 +8,14 @@
 namespace Integration.Tests.Infrastructure;
 
 /// <summary>
-/// No production endpoint passes more than one permission to <c>.RequirePermission()</c>, so this
-/// maps one that does. It appends to the live route builder after <c>next(app)</c> has run
+/// No production endpoint passes more than one permission to <c>.RequirePermission()</c> or gates a
+/// route group with it, so this maps endpoints that do. It appends to the live route builder after <c>next(app)</c> has run
 /// <c>UseRouting()</c>, the same way <c>Integration.Middleware.Tests</c> maps <c>/__test/throw</c>.
 /// </summary>
 public sealed class TestPermissionEndpointStartupFilter : IStartupFilter
 {
     public const string TwoPermissionsPath = "/__test/permissions/two";
+    public const string GroupGatedPath = "/__test/permissions/group/endpoint";
     public const string FirstPermission = IdentityPermissions.Groups.Create;
     public const string SecondPermission = IdentityPermissions.Groups.Delete;
 
@@ -34,6 +35,14 @@ public Action<IApplicationBuilder> Configure(Action<IApplicationBuilder> next)
                 routeBuilder.MapGet(TwoPermissionsPath, () => Results.Ok())
                     .RequireAuthorization()
                     .RequirePermission(FirstPermission, SecondPermission);
+
+                // Group gate (first) + endpoint gate (second): both must apply, the endpoint's
+                // metadata must not replace the group's.
+                routeBuilder.MapGroup("/__test/permissions/group")
+                    .RequireAuthorization()
+                    .RequirePermission(FirstPermission)
+                    .MapGet("/endpoint", () => Results.Ok())
+                    .RequirePermission(SecondPermission);
             }
         };
     }
diff --git a/src/Tests/Integration.Tests/Tests/Authorization/RequirePermissionAllOfTests.cs b/src/Tests/Integration.Tests/Tests/Authorization/RequirePermissionAllOfTests.cs
index 5856fc306d..b3a75acab5 100644
--- a/src/Tests/Integration.Tests/Tests/Authorization/RequirePermissionAllOfTests.cs
+++ b/src/Tests/Integration.Tests/Tests/Authorization/RequirePermissionAllOfTests.cs
@@ -9,9 +9,10 @@
 namespace Integration.Tests.Tests.Authorization;
 
 /// <summary>
-/// <c>.RequirePermission(a, b)</c> must demand every listed permission. Probed through
-/// <see cref="TestPermissionEndpointStartupFilter.TwoPermissionsPath"/>, a test-only endpoint,
-/// because no production endpoint lists more than one.
+/// <c>.RequirePermission(a, b)</c> must demand every listed permission, and a route group's
+/// <c>.RequirePermission(a)</c> must still apply when an endpoint inside it adds <c>.RequirePermission(b)</c>.
+/// Probed through test-only endpoints from <see cref="TestPermissionEndpointStartupFilter"/>, because no
+/// production endpoint lists more than one permission or gates a group.
 /// </summary>
 [Collection(FshCollectionDefinition.Name)]
 public sealed class RequirePermissionAllOfTests
@@ -51,6 +52,44 @@ public async Task TwoPermissionEndpoint_Should_Return200_When_UserHoldsBothPermi
             $"Holding every required permission must open the gate: {await response.Content.ReadAsStringAsync()}");
     }
 
+    [Fact]
+    public async Task GroupGatedEndpoint_Should_Return403_When_UserHoldsOnlyTheEndpointPermission()
+    {
+        using var userClient = await CreateUserClientWithPermissionsAsync(
+            "group-endpoint-only", TestPermissionEndpointStartupFilter.SecondPermission);
+
+        var response = await userClient.GetAsync(TestPermissionEndpointStartupFilter.GroupGatedPath);
+
+        response.StatusCode.ShouldBe(HttpStatusCode.Forbidden,
+            "The endpoint's RequirePermission must not replace the route group's gate.");
+    }
+
+    [Fact]
+    public async Task GroupGatedEndpoint_Should_Return403_When_UserHoldsOnlyTheGroupPermission()
+    {
+        using var userClient = await CreateUserClientWithPermissionsAsync(
+            "group-group-only", TestPermissionEndpointStartupFilter.FirstPermission);
+
+        var response = await userClient.GetAsync(TestPermissionEndpointStartupFilter.GroupGatedPath);
+
+        response.StatusCode.ShouldBe(HttpStatusCode.Forbidden,
+            "Holding only the group's permission must not open an endpoint that adds its own gate.");
+    }
+
+    [Fact]
+    public async Task GroupGatedEndpoint_Should_Return200_When_UserHoldsGroupAndEndpointPermissions()
+    {
+        using var userClient = await CreateUserClientWithPermissionsAsync(
+            "group-both",
+            TestPermissionEndpointStartupFilter.FirstPermission,
+            TestPermissionEndpointStartupFilter.SecondPermission);
+
+        var response = await userClient.GetAsync(TestPermissionEndpointStartupFilter.GroupGatedPath);
+
+        response.StatusCode.ShouldBe(HttpStatusCode.OK,
+            $"Holding both the group and endpoint permissions must open the gate: {await response.Content.ReadAsStringAsync()}");
+    }
+
     // ─── helpers ─────────────────────────────────────────────────────
 
     private async Task<HttpClient> CreateUserClientWithPermissionsAsync(string handlePrefix, params string[] permissions)