CVE-2021-32656 Trusted servers exchange can be triggered by attacker

High 8.6 Published 1 Jun 2021 Updated 3 Aug 2024

An attacker can access basic user information via a public link if automatic trusted server addition is enabled in Nextcloud.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2021-32656?

CVE-2021-32656 is a high-severity vulnerability in Nextcloud Nextcloud Server, published on 1 Jun 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Nextcloud Server is a Nextcloud package that handles data storage. A vulnerability in federated share exists in versions prior to 19.0.11, 20.0.10, and 21.0.2. An attacker can gain access to basic information about users of a server by accessing a public link that a legitimate server user added as a federated share. This happens because Nextcloud supports sharing registered users with other Nextcloud servers, which can be done automatically when selecting the "Add server automatically once a federated share was created successfully" setting. The vulnerability is patched in versions 19.0.11, 20.0.10, and 21.0.2 As a workaround, disable "Add server automatically once a federated share was created successfully" in the Nextcloud settings.

Weakness: CWE-284

Which versions are affected by CVE-2021-32656?

It affects 1 product.

Products include Nextcloud Nextcloud Server.

How do I fix CVE-2021-32656?

No fix has been published for CVE-2021-32656 yet. Limit exposure of the affected software until one is available.

Is CVE-2021-32656 being exploited?

There is no known exploitation of CVE-2021-32656 in the wild and no public exploit code.

All Nextcloud Nextcloud Server vulnerabilities

Sources

Also known as GHSA-j875-vr2q-h6x6.