Rate-limits not working on instances without configured memory cache backend

Description

Impact

Nextcloud Server did not implement a database backend for rate-limiting purposes, any component of Nextcloud using rate-limits (as as AnonRateThrottle or UserRateThrottle) was thus not rate limited on instances not having a memory cache backend configured.

In the case of a default installation this would notably include the rate-limits on the two factor codes.

Patches

It is recommended that the Nextcloud Server is upgraded to 20.0.13, 21.0.5 or 22.2.0.

Workarounds

Enable a memory cache backend in config.php, such as shown in our config.sample.php.

References

• HackerOne
• Pull Request

For more information

If you have any questions or comments about this advisory:

• Create a post in nextcloud/security-advisories
• Customers: Open a support ticket at support.nextcloud.com