diff --git a/lib/ACL/ACLManager.php b/lib/ACL/ACLManager.php
index 00055f14a..caa7c7035 100644
--- a/lib/ACL/ACLManager.php
+++ b/lib/ACL/ACLManager.php
@@ -24,6 +24,7 @@
 namespace OCA\GroupFolders\ACL;
 
 use OC\Cache\CappedMemoryCache;
+use OCA\GroupFolders\ACL\UserMapping\IUserMappingManager;
 use OCA\GroupFolders\Trash\TrashManager;
 use OCP\Constants;
 use OCP\Files\IRootFolder;
@@ -35,12 +36,13 @@ class ACLManager {
 	private $rootFolderProvider;
 
 	public function __construct(
-		private RuleManager  $ruleManager,
-		private TrashManager $trashManager,
-		private IUser        $user,
-		callable             $rootFolderProvider,
-		private ?int         $rootStorageId = null,
-		private bool         $inheritMergePerUser = false,
+		private RuleManager         $ruleManager,
+		private TrashManager        $trashManager,
+		private IUserMappingManager $userMappingManager,
+		private IUser               $user,
+		callable                    $rootFolderProvider,
+		private ?int                $rootStorageId = null,
+		private bool                $inheritMergePerUser = false,
 	) {
 		$this->ruleCache = new CappedMemoryCache();
 		$this->rootFolderProvider = $rootFolderProvider;
@@ -104,7 +106,7 @@ private function getRelevantPaths(string $path): array {
 		$fromTrashbin = str_starts_with($path, '__groupfolders/trash/');
 		if ($fromTrashbin) {
 			/* Exploded path will look like ["__groupfolders", "trash", "1", "folderName.d2345678", "rest/of/the/path.txt"] */
-			[,,$groupFolderId,$rootTrashedItemName] = explode('/', $path, 5);
+			[, , $groupFolderId, $rootTrashedItemName] = explode('/', $path, 5);
 			$groupFolderId = (int)$groupFolderId;
 			/* Remove the date part */
 			$separatorPos = strrpos($rootTrashedItemName, '.d');
@@ -152,6 +154,22 @@ public function getACLPermissionsForPath(string $path): int {
 		return $this->calculatePermissionsForPath($rules);
 	}
 
+	/**
+	 * Check what the effective permissions would be for the current user for a path would be with a new set of rules
+	 *
+	 * @param string $path
+	 * @param array $newRules
+	 * @return int
+	 */
+	public function testACLPermissionsForPath(string $path, array $newRules): int {
+		$path = ltrim($path, '/');
+		$rules = $this->getRules($this->getRelevantPaths($path));
+
+		$rules[$path] = $this->filterApplicableRulesToUser($newRules);
+
+		return $this->calculatePermissionsForPath($rules);
+	}
+
 	/**
 	 * @param string $path
 	 * @param array<string, Rule[]> $rules list of rules per path
@@ -235,4 +253,25 @@ public function getPermissionsForTree(string $path): int {
 			return $permissions & $denyMask;
 		}, Constants::PERMISSION_ALL);
 	}
+
+	/**
+	 * Filter a list to only the rules applicable to the current user
+	 *
+	 * @param Rule[] $rules
+	 * @return Rule[]
+	 */
+	private function filterApplicableRulesToUser(array $rules): array {
+		$userMappings = $this->userMappingManager->getMappingsForUser($this->user);
+		return array_values(array_filter($rules, function(Rule $rule) use ($userMappings) {
+			foreach ($userMappings as $userMapping) {
+				if (
+					$userMapping->getType() == $rule->getUserMapping()->getType() &&
+					$userMapping->getId() == $rule->getUserMapping()->getId()
+				) {
+					return true;
+				}
+			}
+			return false;
+		}));
+	}
 }
diff --git a/lib/ACL/ACLManagerFactory.php b/lib/ACL/ACLManagerFactory.php
index 11ea7ddfb..0a1f1979e 100644
--- a/lib/ACL/ACLManagerFactory.php
+++ b/lib/ACL/ACLManagerFactory.php
@@ -23,6 +23,7 @@
 
 namespace OCA\GroupFolders\ACL;
 
+use OCA\GroupFolders\ACL\UserMapping\IUserMappingManager;
 use OCA\GroupFolders\Trash\TrashManager;
 use OCP\IConfig;
 use OCP\IUser;
@@ -34,6 +35,7 @@ public function __construct(
 		private RuleManager $ruleManager,
 		private TrashManager $trashManager,
 		private IConfig $config,
+		private IUserMappingManager $userMappingManager,
 		callable $rootFolderProvider,
 	) {
 		$this->rootFolderProvider = $rootFolderProvider;
@@ -43,6 +45,7 @@ public function getACLManager(IUser $user, ?int $rootStorageId = null): ACLManag
 		return new ACLManager(
 			$this->ruleManager,
 			$this->trashManager,
+			$this->userMappingManager,
 			$user,
 			$this->rootFolderProvider,
 			$rootStorageId,
diff --git a/lib/AppInfo/Application.php b/lib/AppInfo/Application.php
index 46f82cf42..44d661010 100644
--- a/lib/AppInfo/Application.php
+++ b/lib/AppInfo/Application.php
@@ -225,6 +225,7 @@ public function register(IRegistrationContext $context): void {
 				$c->get(RuleManager::class),
 				$c->get(TrashManager::class),
 				$c->get(IConfig::class),
+				$c->get(IUserMappingManager::class),
 				$rootFolderProvider
 			);
 		});
diff --git a/lib/DAV/ACLPlugin.php b/lib/DAV/ACLPlugin.php
index 2d99f714c..aab9d98f5 100644
--- a/lib/DAV/ACLPlugin.php
+++ b/lib/DAV/ACLPlugin.php
@@ -24,6 +24,8 @@
 namespace OCA\GroupFolders\DAV;
 
 use OCA\DAV\Connector\Sabre\Node;
+use OCA\GroupFolders\ACL\ACLManager;
+use OCA\GroupFolders\ACL\ACLManagerFactory;
 use OCA\GroupFolders\ACL\Rule;
 use OCA\GroupFolders\ACL\RuleManager;
 use OCA\GroupFolders\Folder\FolderManager;
@@ -31,6 +33,7 @@
 use OCP\Constants;
 use OCP\IUser;
 use OCP\IUserSession;
+use Sabre\DAV\Exception\BadRequest;
 use Sabre\DAV\INode;
 use Sabre\DAV\PropFind;
 use Sabre\DAV\PropPatch;
@@ -46,19 +49,14 @@ class ACLPlugin extends ServerPlugin {
 	public const GROUP_FOLDER_ID = '{http://nextcloud.org/ns}group-folder-id';
 
 	private ?Server $server = null;
-	private RuleManager $ruleManager;
-	private FolderManager $folderManager;
-	private IUserSession $userSession;
 	private ?IUser $user = null;
 
 	public function __construct(
-		RuleManager $ruleManager,
-		IUserSession $userSession,
-		FolderManager $folderManager
+		private RuleManager $ruleManager,
+		private IUserSession $userSession,
+		private FolderManager $folderManager,
+		private ACLManagerFactory $aclManagerFactory,
 	) {
-		$this->ruleManager = $ruleManager;
-		$this->userSession = $userSession;
-		$this->folderManager = $folderManager;
 	}
 
 	private function isAdmin(string $path): bool {
@@ -72,7 +70,7 @@ private function isAdmin(string $path): bool {
 
 	public function initialize(Server $server): void {
 		$this->server = $server;
-		$this->user = $user = $this->userSession->getUser();
+		$this->user = $this->userSession->getUser();
 
 		$this->server->on('propFind', [$this, 'propFind']);
 		$this->server->on('propPatch', [$this, 'propPatch']);
@@ -211,6 +209,12 @@ public function propPatch(string $path, PropPatch $propPatch): void {
 				);
 			}, $rawRules);
 
+			$aclManager = $this->aclManagerFactory->getACLManager($this->user);
+			$newPermissions = $aclManager->testACLPermissionsForPath($fileInfo->getPath(), $rules);
+			if (!($newPermissions & Constants::PERMISSION_READ)) {
+				throw new BadRequest("Request would revoke permissions for current user");
+			}
+
 			$existingRules = array_reduce(
 				$this->ruleManager->getAllRulesForPaths($mount->getNumericStorageId(), [$path]),
 				function (array $rules, array $rulesForPath) {