CVE-2021-37631 Circle can be accessed by non-Circle members in Nextcloud Deck

Medium 6.5 Published 7 Sep 2021 Updated 4 Aug 2024

Attackers can access boards shared with a Circle without being members, exposing sensitive project data in Nextcloud Deck.

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

What is CVE-2021-37631?

CVE-2021-37631 is a medium-severity missing authorization vulnerability in nextcloud security-advisories, published on 7 Sep 2021. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

Deck is an open source kanban style organization tool aimed at personal planning and project organization for teams integrated with Nextcloud. In affected versions the Deck application didn't properly check membership of users in a Circle. This allowed other users in the instance to gain access to boards that have been shared with a Circle, even if the user was not a member of the circle. It is recommended that Nextcloud Deck is upgraded to 1.5.1, 1.4.4 or 1.2.9. If you are unable to update it is advised to disable the Deck plugin.

Weakness: CWE-639

Which versions are affected by CVE-2021-37631?

It affects 1 product.

Products include Nextcloud Deck.

How do I fix CVE-2021-37631?

No fix has been published for CVE-2021-37631 yet. Limit exposure of the affected software until one is available.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2021-37631 being exploited?

There is no known exploitation of CVE-2021-37631 in the wild and no public exploit code.

Sources

Also known as GHSA-4mxp-j277-82hr.