CVE-2021-41177: Rate-limits not working on instances without configured memory cache backend
First published: Mon Oct 25 2021(Updated: )
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 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. It is recommended that the Nextcloud Server be upgraded to 20.0.13, 21.0.5, or 22.2.0. As a workaround, enable a memory cache backend in `config.php`.
Credit: security-advisories@github.com security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Nextcloud Nextcloud Server | <20.0.13 | |
| Nextcloud Nextcloud Server | >=21.0.0<21.0.5 | |
| Nextcloud Nextcloud Server | >=22.0.0<22.2.0 | |
| <20.0.13 | ||
| >=21.0.0<21.0.5 | ||
| >=22.0.0<22.2.0 |
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Reference Links
Frequently Asked Questions
What is the severity of CVE-2021-41177?
CVE-2021-41177 is classified as a medium severity vulnerability affecting specific versions of Nextcloud Server.
How do I fix CVE-2021-41177?
To fix CVE-2021-41177, upgrade to Nextcloud Server version 20.0.13, 21.0.5, or 22.2.0 or higher.
What components of Nextcloud are affected by CVE-2021-41177?
CVE-2021-41177 affects any component of Nextcloud that utilizes rate-limiting features such as AnonRateThrottle or UserRateThrottle.
What are the risks associated with CVE-2021-41177?
The risks include potential abuse of rate limits, leading to denial of service or unauthorized access to user data.
Can CVE-2021-41177 be exploited remotely?
Yes, CVE-2021-41177 can be exploited remotely, allowing attackers to bypass rate limitations.
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