From b05a456838a6e4768ad18780f45d497adb27f61c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=B4me=20Chilliet?= <come.chilliet@nextcloud.com>
Date: Mon, 3 Aug 2026 16:38:26 +0200
Subject: [PATCH] fix(share): Avoid crash when share owner is not found
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IShare::getNode is documented to throw only NotFoundException, so catch
 UserNotFoundException from the level below and wrap it. This avoids
 crashes from share api controller when listing shares and one of them
 is broken because its owner has vanished from the backend.

Signed-off-by: Côme Chilliet <come.chilliet@nextcloud.com>
---
 lib/private/Share20/Share.php | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/lib/private/Share20/Share.php b/lib/private/Share20/Share.php
index 2ededbc7c361a..b87a3d1106530 100644
--- a/lib/private/Share20/Share.php
+++ b/lib/private/Share20/Share.php
@@ -5,8 +5,10 @@
  * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
  * SPDX-License-Identifier: AGPL-3.0-only
  */
+
 namespace OC\Share20;
 
+use OC\User\NoUserException;
 use OCP\Constants;
 use OCP\Files\Cache\ICacheEntry;
 use OCP\Files\File;
@@ -133,20 +135,24 @@ public function getNode(): Node {
 				throw new NotFoundException();
 			}
 
-			// for federated shares the owner can be a remote user, in this
-			// case we use the initiator
-			if ($this->userManager->userExists($this->shareOwner)) {
-				$userFolder = $this->rootFolder->getUserFolder($this->shareOwner);
-			} else {
-				$userFolder = $this->rootFolder->getUserFolder($this->sharedBy);
+			try {
+				// for federated shares the owner can be a remote user, in this
+				// case we use the initiator
+				if ($this->userManager->userExists($this->shareOwner)) {
+					$userFolder = $this->rootFolder->getUserFolder($this->shareOwner);
+				} else {
+					$userFolder = $this->rootFolder->getUserFolder($this->sharedBy);
+				}
+
+				$node = $userFolder->getFirstNodeById($this->fileId);
+				if (!$node) {
+					throw new NotFoundException('Node for share not found, fileid: ' . $this->fileId);
+				}
+
+				$this->node = $node;
+			} catch (NoUserException $e) {
+				throw new NotFoundException('Owner for share not found, fileid: ' . $this->fileId, previous:$e);
 			}
-
-			$node = $userFolder->getFirstNodeById($this->fileId);
-			if (!$node) {
-				throw new NotFoundException('Node for share not found, fileid: ' . $this->fileId);
-			}
-
-			$this->node = $node;
 		}
 
 		return $this->node;