Nextcloud Server is a data storage system for Nextcloud, a self-hosted productivity platform. When multiple requests are sent in parallel, all of them were executed even if the amount of faulty requests succeeded the limit by the time the response was sent to the client. This allowed someone to send as many requests the server could handle in parallel to bruteforce protected details instead of the configured limit, default 8. Nextcloud Server versions 25.0.7 and 26.0.2 and Nextcloud Enterprise Server versions 21.0.9.12, 22.2.10.12, 23.0.12.7, 24.0.12.2, 25.0.7 and 26.0.2 contain patches for this issue.
The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame, making it more susceptible to brute force attacks.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Nextcloud_server | Nextcloud | 21.0.0 (including) | 21.0.9.12 (excluding) |
| Nextcloud_server | Nextcloud | 22.0.0 (including) | 22.2.10.12 (excluding) |
| Nextcloud_server | Nextcloud | 23.0.0 (including) | 23.0.12.7 (excluding) |
| Nextcloud_server | Nextcloud | 24.0.0 (including) | 24.0.12.2 (excluding) |
| Nextcloud_server | Nextcloud | 25.0.0 (including) | 25.0.7 (excluding) |
| Nextcloud_server | Nextcloud | 26.0.0 (including) | 26.0.2 (excluding) |
Common protection mechanisms include:
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator. [REF-45]