Impact
The Nextcloud Text application shipped with Nextcloud server did use a text/html Content-Type when serving files to users.
Due the strict Content-Security-Policy shipped with Nextcloud, this issue is not exploitable on modern browsers supporting Content-Security-Policy.
Patches
It is recommended that the Nextcloud Server is upgraded to 19.0.13, 20.0.11 or 21.0.3
Workarounds
Use a browser that has support for Content-Security-Policy. You can find a list of supported browsers on caniuse.com. A notable exemption is Internet Explorer which does not support CSP properly.
References
For more information
If you have any questions or comments about this advisory:
Impact
The Nextcloud Text application shipped with Nextcloud server did use a
text/htmlContent-Type when serving files to users.Due the strict Content-Security-Policy shipped with Nextcloud, this issue is not exploitable on modern browsers supporting Content-Security-Policy.
Patches
It is recommended that the Nextcloud Server is upgraded to 19.0.13, 20.0.11 or 21.0.3
Workarounds
Use a browser that has support for Content-Security-Policy. You can find a list of supported browsers on caniuse.com. A notable exemption is Internet Explorer which does not support CSP properly.
References
For more information
If you have any questions or comments about this advisory: