diff --git a/__tests__/permissions.test.ts b/__tests__/permissions.test.ts
index 8b8eb29..c3e8d5c 100644
--- a/__tests__/permissions.test.ts
+++ b/__tests__/permissions.test.ts
@@ -4,6 +4,8 @@ import {
   ADMIN_ROLES,
   TREASURER_ROLES,
   ACTIVE_STATUSES,
+  PRIVILEGE_STATUSES,
+  isPrivilegeEligible,
   hasRole,
   type Role,
 } from '@/lib/permissions'
@@ -50,6 +52,22 @@ describe('ACTIVE_STATUSES', () => {
   })
 })
 
+describe('isPrivilegeEligible / PRIVILEGE_STATUSES', () => {
+  it('only current + late may exercise a role/permission', () => {
+    expect([...PRIVILEGE_STATUSES].sort()).toEqual(['current', 'late'].sort())
+    expect(isPrivilegeEligible('current')).toBe(true)
+    expect(isPrivilegeEligible('late')).toBe(true)
+  })
+  it('unverified (pending approval) is NOT privilege-eligible', () => {
+    expect(isPrivilegeEligible('unverified')).toBe(false)
+  })
+  it('inactive / null / undefined are NOT privilege-eligible', () => {
+    expect(isPrivilegeEligible('inactive')).toBe(false)
+    expect(isPrivilegeEligible(null)).toBe(false)
+    expect(isPrivilegeEligible(undefined)).toBe(false)
+  })
+})
+
 describe('hasRole', () => {
   it('returns true when role is in the allowed list', () => {
     expect(hasRole('admin', ADMIN_ROLES)).toBe(true)
diff --git a/lib/auth-actions.ts b/lib/auth-actions.ts
index 445d947..1d18cc9 100644
--- a/lib/auth-actions.ts
+++ b/lib/auth-actions.ts
@@ -4,6 +4,7 @@ import { createClient } from '@/lib/supabase/server'
 import { createAdminClient } from '@/lib/supabase/admin'
 import { redirect } from 'next/navigation'
 import { checkRateLimit, sanitizeString, sanitizeSlug } from '@/lib/security'
+import { ACTIVE_STATUSES } from '@/lib/permissions'
 
 function generateInviteCode() {
   // Cryptographically random, and wider (8 chars) so the code space is not
@@ -157,6 +158,19 @@ export async function joinSpace(formData: {
       ? invite.role
       : 'member'
 
+  // Single active membership per user (the product's locked single-space
+  // model; getAuthMember's .single() fails closed on 2+). Reject a second
+  // join rather than letting it self-DoS the user out of every action.
+  const { data: existingMembership } = await admin
+    .from('space_members')
+    .select('id')
+    .eq('user_id', user.id)
+    .in('status', ACTIVE_STATUSES as unknown as string[])
+    .maybeSingle()
+  if (existingMembership) {
+    return { error: 'You are already a member of a space.' }
+  }
+
   const { data: newMember, error: memberErr } = await admin
     .from('space_members')
     .insert({
diff --git a/lib/auth-helpers.ts b/lib/auth-helpers.ts
index 1e3185f..4710218 100644
--- a/lib/auth-helpers.ts
+++ b/lib/auth-helpers.ts
@@ -1,7 +1,7 @@
 import type { SupabaseClient } from '@supabase/supabase-js'
 import type { Tables } from '@/types/database'
 import type { ZodSchema } from 'zod'
-import { ACTIVE_STATUSES, hasRole, type Role } from '@/lib/permissions'
+import { ACTIVE_STATUSES, hasRole, isPrivilegeEligible, type Role } from '@/lib/permissions'
 
 /**
  * Loose Supabase client type for shared helpers.
@@ -20,7 +20,7 @@ export type ServerSupabase = SupabaseClient<any, any, any>
 /** Projection of `space_members` that server actions consume. */
 export type Member = Pick<
   Tables<'space_members'>,
-  'id' | 'space_id' | 'user_id' | 'role' | 'display_name' | 'handle'
+  'id' | 'space_id' | 'user_id' | 'role' | 'status' | 'display_name' | 'handle'
 >
 
 /**
@@ -50,7 +50,7 @@ export async function getAuthMember(supabase: ServerSupabase): Promise<Member |
   // explicit active-space selector before this can change.
   const { data } = await supabase
     .from('space_members')
-    .select('id, space_id, user_id, role, display_name, handle')
+    .select('id, space_id, user_id, role, status, display_name, handle')
     .eq('user_id', user.id)
     .in('status', ACTIVE_STATUSES as unknown as string[])
     .single()
@@ -79,6 +79,13 @@ export async function requireMemberWithRole(
 ): Promise<MemberResult> {
   const r = await requireMember(supabase)
   if (!r.ok) return r
+  // require_approval gate: an 'unverified' member holds NO privileged
+  // capability until an admin approves them, even if they redeemed a
+  // role-bearing invite. Without this, redeeming an admin invite into a
+  // require_approval space granted instant admin.
+  if (!isPrivilegeEligible(r.member.status)) {
+    return { ok: false, error: 'Your membership is pending approval.' }
+  }
   if (!hasRole(r.member.role, allowed)) {
     return { ok: false, error: errorLabel }
   }
diff --git a/lib/permissions.ts b/lib/permissions.ts
index 91f0e41..32858a1 100644
--- a/lib/permissions.ts
+++ b/lib/permissions.ts
@@ -24,6 +24,20 @@ export const ALL_ROLES = ROLES
 /** Statuses a member may have and still be allowed to act in the app. */
 export const ACTIVE_STATUSES = ['current', 'unverified', 'late'] as const satisfies readonly MemberStatus[]
 
+/**
+ * Statuses that may exercise a ROLE or PERMISSION (privileged actions).
+ * Deliberately excludes 'unverified': a member of a `require_approval` space
+ * is 'unverified' until an admin approves them, and must hold NO privileged
+ * capability in that window even if they redeemed a role-bearing invite
+ * (otherwise `require_approval` is silently void). 'late' keeps its role
+ * (dues lapse is grace -> late, never an authz downgrade).
+ */
+export const PRIVILEGE_STATUSES = ['current', 'late'] as const satisfies readonly MemberStatus[]
+
+export function isPrivilegeEligible(status: MemberStatus | null | undefined): boolean {
+  return status === 'current' || status === 'late'
+}
+
 /**
  * Returns true if `role` is one of the `allowed` roles.
  * Use this everywhere instead of `role === 'admin' || role === 'board'` chains.