CVE-2023-28833: Unrestricted filenames for logo or favicon as admin in the theming settings in nextcloud server
First published: Thu Mar 30 2023(Updated: )
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.
Credit: security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Nextcloud Nextcloud Server | >=23.0.0<23.0.14 | |
| Nextcloud Nextcloud Server | >=24.0.0<24.0.10 | |
| Nextcloud Nextcloud Server | >=24.0.0<24.0.10 | |
| Nextcloud Nextcloud Server | >=25.0.0<25.0.4 | |
| Nextcloud Nextcloud Server | >=25.0.0<25.0.4 |
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Reference Links
Frequently Asked Questions
What is CVE-2023-28833?
CVE-2023-28833 is a vulnerability in Nextcloud server that allows admins to overwrite files in the appdata directory by uploading a logo or favicon with a unrestricted file name.
Which versions of Nextcloud server are affected by CVE-2023-28833?
Versions 23.0.0 to 23.0.14, 24.0.0 to 24.0.10, and 25.0.0 to 25.0.4 of Nextcloud server are affected by CVE-2023-28833.
What is the severity of CVE-2023-28833?
CVE-2023-28833 has a severity score of 8.8 (High).
How can I fix CVE-2023-28833?
To fix CVE-2023-28833, users should update to the latest version of Nextcloud server.
Where can I find more information about CVE-2023-28833?
You can find more information about CVE-2023-28833 in the Nextcloud security advisories and the GitHub pull request.
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- version/nextcloud nextcloud server/23.0.0
- version/nextcloud nextcloud server/24.0.0
- version/nextcloud nextcloud server/25.0.0