CVE-2026-73509: OpenList: Authenticated users can rename files outside their base path via batch rename `src_name` traversal

OpenList a file list program that supports multiple storage. Prior to 4.2.4, the authenticated /api/fs/batchrename handler in server/handles/fsbatch.go authorizes only the source directory produced by user.JoinPath(req.SrcDir) and validates renameObject.NewName with checkRelativePath, but does not validate attacker-controlled renameObject.SrcName, supplied as srcname, before concatenating it with the authorized path and passing the result to fs.Rename. A user with rename permission can use traversal segments in srcname to make path normalization select a file outside the authorized directory and configured base path, resulting in cross-user file integrity loss, limited availability impact, and file-existence disclosure through success or error responses. This issue is fixed in version 4.2.4.