Nextcloud · Nextcloud Server · CVE-2021-41177
**Name of the Vulnerable Software and Affected Versions**
Nextcloud Server versions prior to 20.0.13
Nextcloud Server versions prior to 21.0.5
Nextcloud Server versions prior to 22.2.0
**Description**
Nextcloud is an open-source, self-hosted productivity platform. Prior to versions 20.0.13, 21.0.5, and 22.2.0, Nextcloud Server did not implement a database backend for rate-limiting purposes. Any component of Nextcloud using rate-limits (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.
**Recommendations**
Upgrade Nextcloud Server to version 20.0.13
Upgrade Nextcloud Server to version 21.0.5
Upgrade Nextcloud Server to version 22.2.0
As a workaround, enable a memory cache backend in `config.php`