diff --git a/lib/Controller/DsgvoController.php b/lib/Controller/DsgvoController.php
index da343a0..40c2f83 100644
--- a/lib/Controller/DsgvoController.php
+++ b/lib/Controller/DsgvoController.php
@@ -11,7 +11,6 @@ use OCA\Mitgliederverwaltung\Service\ValidationException;
 use OCP\AppFramework\ApiController;
 use OCP\AppFramework\Db\DoesNotExistException;
 use OCP\AppFramework\Http;
-use OCP\AppFramework\Http\Attribute\NoCSRFRequired;
 use OCP\AppFramework\Http\DataDownloadResponse;
 use OCP\AppFramework\Http\JSONResponse;
 use OCP\IRequest;
@@ -58,7 +57,6 @@ class DsgvoController extends ApiController {
      * POST /api/v1/members/{id}/dsgvo-export
      * Body: { "password": "..." }
      */
-    #[NoCSRFRequired]
     public function export(int $id): DataDownloadResponse|JSONResponse {
         try {
             $this->assertAdmin();
@@ -119,7 +117,6 @@ class DsgvoController extends ApiController {
      * DELETE /api/v1/members/{id}/dsgvo-delete
      * Body: { "confirm": true }
      */
-    #[NoCSRFRequired]
     public function hardDelete(int $id): JSONResponse {
         try {
             $this->assertAdmin();
diff --git a/lib/Controller/ExportController.php b/lib/Controller/ExportController.php
index 980bac3..7525ae4 100644
--- a/lib/Controller/ExportController.php
+++ b/lib/Controller/ExportController.php
@@ -155,7 +155,6 @@ class ExportController extends ApiController {
      * POST /api/v1/export/members/encrypted
      * Body: { "password": "...", "status": "aktiv" }
      */
-    #[NoCSRFRequired]
     public function membersEncrypted(): DataDownloadResponse|JSONResponse {
         try {
             $password = $this->request->getParam('password');
@@ -204,7 +203,6 @@ class ExportController extends ApiController {
      * POST /api/v1/export/fees/encrypted
      * Body: { "password": "...", "year": 2026 }
      */
-    #[NoCSRFRequired]
     public function feesEncrypted(): DataDownloadResponse|JSONResponse {
         try {
             $password = $this->request->getParam('password');
@@ -260,7 +258,6 @@ class ExportController extends ApiController {
      * POST /api/v1/export/birthdays/encrypted
      * Body: { "password": "...", "month": 4 }
      */
-    #[NoCSRFRequired]
     public function birthdaysEncrypted(): DataDownloadResponse|JSONResponse {
         try {
             $password = $this->request->getParam('password');
@@ -354,7 +351,6 @@ class ExportController extends ApiController {
      *
      * Requires explicit confirmation because sensitive data is decrypted.
      */
-    #[NoCSRFRequired]
     public function bundleSensitive(): DataDownloadResponse|JSONResponse {
         try {
             $confirm = $this->request->getParam('confirm');
@@ -448,7 +444,6 @@ class ExportController extends ApiController {
      * POST /api/v1/export/banking/encrypted
      * Body: { "password": "..." }
      */
-    #[NoCSRFRequired]
     public function bankingEncrypted(): DataDownloadResponse|JSONResponse {
         try {
             // Permission check: banking visibility required
diff --git a/lib/Controller/ReportController.php b/lib/Controller/ReportController.php
index e59fc17..4ce717a 100644
--- a/lib/Controller/ReportController.php
+++ b/lib/Controller/ReportController.php
@@ -163,7 +163,6 @@ class ReportController extends ApiController {
      * POST /api/v1/reports/{type}/encrypted
      * Body: { "password": "...", ...params }
      */
-    #[NoCSRFRequired]
     public function encrypted(string $type): DataDownloadResponse|JSONResponse {
         try {
             $password = $this->request->getParam('password');
diff --git a/tests/Unit/CsrfProtectionTest.php b/tests/Unit/CsrfProtectionTest.php
new file mode 100644
index 0000000..56ce9fd
--- /dev/null
+++ b/tests/Unit/CsrfProtectionTest.php
@@ -0,0 +1,132 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\Mitgliederverwaltung\Tests\Unit;
+
+use OCP\AppFramework\Http\Attribute\NoCSRFRequired;
+use PHPUnit\Framework\TestCase;
+use ReflectionClass;
+
+/**
+ * Verify that POST/DELETE endpoints do NOT have #[NoCSRFRequired].
+ *
+ * GET endpoints may legitimately skip CSRF checks (standard Nextcloud practice).
+ * POST/DELETE endpoints must have CSRF protection enabled (no #[NoCSRFRequired]).
+ *
+ * Part of Issue #171.
+ */
+class CsrfProtectionTest extends TestCase {
+
+    /**
+     * Map of controller class => method names that are POST/DELETE and
+     * MUST NOT have #[NoCSRFRequired].
+     */
+    private function getPostDeleteEndpoints(): array {
+        return [
+            // ExportController — encrypted exports use POST
+            \OCA\Mitgliederverwaltung\Controller\ExportController::class => [
+                'membersEncrypted',
+                'feesEncrypted',
+                'birthdaysEncrypted',
+                'bundleSensitive',
+                'bankingEncrypted',
+            ],
+            // ReportController — encrypted report uses POST
+            \OCA\Mitgliederverwaltung\Controller\ReportController::class => [
+                'encrypted',
+            ],
+            // DsgvoController — export (POST) and hardDelete (DELETE)
+            \OCA\Mitgliederverwaltung\Controller\DsgvoController::class => [
+                'export',
+                'hardDelete',
+            ],
+        ];
+    }
+
+    /**
+     * Map of controller class => method names that are GET and
+     * MAY have #[NoCSRFRequired] (read-only endpoints).
+     */
+    private function getGetEndpoints(): array {
+        return [
+            \OCA\Mitgliederverwaltung\Controller\ExportController::class => [
+                'members',
+                'fees',
+                'birthdays',
+                'bundle',
+                'entityTypes',
+                'entity',
+            ],
+            \OCA\Mitgliederverwaltung\Controller\ReportController::class => [
+                'index',
+                'preview',
+                'pdf',
+            ],
+        ];
+    }
+
+    /**
+     * @dataProvider postDeleteEndpointsProvider
+     */
+    public function testPostDeleteEndpointsRequireCsrf(string $controllerClass, string $method): void {
+        $rc = new ReflectionClass($controllerClass);
+        $rm = $rc->getMethod($method);
+
+        $attrs = $rm->getAttributes(NoCSRFRequired::class);
+
+        $this->assertEmpty(
+            $attrs,
+            sprintf(
+                '%s::%s is a POST/DELETE endpoint but has #[NoCSRFRequired] — '
+                . 'this bypasses CSRF protection on a state-changing endpoint.',
+                $controllerClass,
+                $method
+            )
+        );
+    }
+
+    /**
+     * @dataProvider getEndpointsProvider
+     */
+    public function testGetEndpointsAllowNoCsrf(string $controllerClass, string $method): void {
+        $rc = new ReflectionClass($controllerClass);
+        $rm = $rc->getMethod($method);
+
+        $attrs = $rm->getAttributes(NoCSRFRequired::class);
+
+        $this->assertNotEmpty(
+            $attrs,
+            sprintf(
+                '%s::%s is a GET (read-only) endpoint and should have #[NoCSRFRequired] '
+                . 'for compatibility with Nextcloud API calls.',
+                $controllerClass,
+                $method
+            )
+        );
+    }
+
+    public static function postDeleteEndpointsProvider(): array {
+        $data = [];
+        $endpoints = (new self('dummy'))->getPostDeleteEndpoints();
+        foreach ($endpoints as $class => $methods) {
+            foreach ($methods as $method) {
+                $shortClass = (new ReflectionClass($class))->getShortName();
+                $data["$shortClass::$method"] = [$class, $method];
+            }
+        }
+        return $data;
+    }
+
+    public static function getEndpointsProvider(): array {
+        $data = [];
+        $endpoints = (new self('dummy'))->getGetEndpoints();
+        foreach ($endpoints as $class => $methods) {
+            foreach ($methods as $method) {
+                $shortClass = (new ReflectionClass($class))->getShortName();
+                $data["$shortClass::$method"] = [$class, $method];
+            }
+        }
+        return $data;
+    }
+}