Nextcloud 4.3.05.2.6: Unauthorized File Read by Removed Collaborator
CVE-2026-45543 Published on June 1, 2026
Nextcloud: Deleting a Forms collaborator share leaves uploaded response files accessible through a lingering Files share
Nextcloud is an open source content collaboration platform. From version 4.3.0 to before version 5.2.7, a removed collaborator retains unauthorized read access to uploaded respondent files for the affected form. The scope is limited to uploaded files for forms where that user previously had results access. This issue has been patched in version 5.2.7.
Vulnerability Analysis
CVE-2026-45543 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.
Weakness Type
Files or Directories Accessible to External Parties
The product makes files or directories accessible to unauthorized actors, even though they should not be. Web servers, FTP servers, and similar servers may store a set of files underneath a "root" directory that is accessible to the server's users. Applications may store sensitive files underneath this root without also using access control to limit which users may request those files, if any. Alternately, an application might package multiple files or directories into an archive file (e.g., ZIP or tar), but the application might not exclude sensitive files that are underneath those directories.