CVE-2023-28999 Nextcloud: Lack of authenticity of metadata keys allows a malicious server to gain access to E2EE folders
A malicious server admin can bypass E2EE protections to decrypt, read, and modify files in encrypted folders via Nextcloud clients.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2023-28999?
CVE-2023-28999 is a medium-severity missing authorization vulnerability in nextcloud security-advisories, published on 4 Apr 2023. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
Nextcloud is an open-source productivity platform. In Nextcloud Desktop client 3.0.0 until 3.8.0, Nextcloud Android app 3.13.0 until 3.25.0, and Nextcloud iOS app 3.0.5 until 4.8.0, a malicious server administrator can gain full access to an end-to-end encrypted folder. They can decrypt files, recover the folder structure and add new files. This issue is fixed in Nextcloud Desktop 3.8.0, Nextcloud Android 3.25.0, and Nextcloud iOS 4.8.0. No known workarounds are available.
Which versions are affected by CVE-2023-28999?
1 open source package ship an affected version, including nextcloud. It affects 2 products.
| Package | Affected | Fixed in |
|---|---|---|
nextcloud Bitnami | From 3.0.5 | 4.8.0 |
Products include Nextcloud Desktop, Nextcloud Nextcloud.
How do I fix CVE-2023-28999?
Upgrade nextcloud to 4.8.0 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2023-28999 being exploited?
There is no known exploitation of CVE-2023-28999 in the wild and no public exploit code.
Other vulnerabilities in nextcloud security-advisories
Sources
Also known as BIT-nextcloud-2023-28999, DEBIAN-CVE-2023-28999, GHSA-8875-wxww-3rr8, UBUNTU-CVE-2023-28999.