CVE-2026-45283 Nextcloud: Files Lock app allows users to lock and unlock files of other users
Authenticated users can lock or unlock other users' files and bypass token-based locks due to improper ownership validation in the Files Lock app.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-45283?
CVE-2026-45283 is a medium-severity missing authorization vulnerability in Nextcloud Nextcloud Server, published on 1 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.2, and 33.0.0 to before 33.0.1, the files_lock app did not properly validate the ownership of files when processing DAV lock and unlock requests. An authenticated user could lock or unlock files belonging to other users by targeting their absolute WebDAV paths. Additionally, lock tokens were disclosed to unauthorized callers in error responses, allowing attackers to remove token-based locks placed by other users' client applications. It is recommended that the Nextcloud Server is upgraded to 32.0.2 or 33.0.1. It is recommended that the Nextcloud Enterprise Server is upgraded to 31.0.14.4 or 32.0.2 or 33.0.1
Weakness: CWE-287
Which versions are affected by CVE-2026-45283?
It affects 1 product.
Products include Nextcloud Nextcloud Server.
How do I fix CVE-2026-45283?
No fix has been published for CVE-2026-45283 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-45283 being exploited?
There is no known exploitation of CVE-2026-45283 in the wild and no public exploit code.
Other vulnerabilities in Nextcloud Nextcloud Server
- CVE-2021-32802 Preview generation used third-party library not suited for user-generated content in Nextcloud server
- CVE-2023-26482 Scope of workflow operations is not validated in nextcloud server
- CVE-2018-3775 Auth bypass in Nextcloud Server
- CVE-2023-35172 Nextcloud Server password reset endpoint is not brute force protected
- CVE-2023-32320 Nextcloud Server's brute force protection allows someone to send more requests than intended
Sources
Also known as GHSA-4chh-6mhf-p4jj.