CVE-2023-28833 Unrestricted filenames for logo or favicon as admin in the theming settings in nextcloud server

Low 2.4 Published 30 Mar 2023 Updated 11 Feb 2025

Admins can overwrite files in the appdata directory via unrestricted filenames in logo or favicon uploads, potentially allowing malicious file replacement.

Exploited in the wild: Not known
Login needed: An administrator
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2023-28833?

CVE-2023-28833 is a low-severity path traversal vulnerability in Nextcloud Nextcloud Server, published on 30 Mar 2023. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

Official description

Nextcloud server is an open source home cloud implementation. In affected versions admins of a server were able to upload a logo or a favicon and to provided a file name which was not restricted and could overwrite files in the appdata directory. Administrators may have access to overwrite these files by other means but this method could be exploited by tricking an admin into uploading a maliciously named file. It is recommended that the Nextcloud Server is upgraded to 24.0.10 or 25.0.4. Users unable to upgrade should avoid ingesting logo files from untrusted sources.

Weakness: CWE-434, CWE-22

Which versions are affected by CVE-2023-28833?

It affects 1 product.

Products include Nextcloud Nextcloud Server.

How do I fix CVE-2023-28833?

No fix has been published for CVE-2023-28833 yet. Limit exposure of the affected software until one is available.

Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.

Is CVE-2023-28833 being exploited?

There is no known exploitation of CVE-2023-28833 in the wild and no public exploit code.

All Nextcloud Nextcloud Server vulnerabilities

Sources

Also known as GHSA-ch7f-px7m-hg25.