Merge pull request #28481 from nextcloud/fix/hash-key

Hash cache key

lib/private/User/Manager.php

@@ -158,7 +158,7 @@ public function get($uid) {
 			return $this->cachedUsers[$uid];
 		}
 
-		$cachedBackend = $this->cache->get($uid);
+		$cachedBackend = $this->cache->get(sha1($uid));
 		if ($cachedBackend !== null && isset($this->backends[$cachedBackend])) {
 			// Cache has the info of the user backend already, so ask that one directly
 			$backend = $this->backends[$cachedBackend];
@@ -174,7 +174,8 @@ public function get($uid) {
 			}
 
 			if ($backend->userExists($uid)) {
-				$this->cache->set($uid, $i, 300);
+				// Hash $uid to ensure that only valid characters are used for the cache key
+				$this->cache->set(sha1($uid), $i, 300);
 				return $this->getUserObject($uid, $backend);
 			}
 		}