CVE-2021-32656: Nextcloud Server

High severity, CVSS 8.6. EPSS: 1.8% chance of exploitation in the next 30 days.

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.

Affected products

• Nextcloud Nextcloud Server: before 19.0.11 (fixed in 19.0.11); from 20.0.0, before 20.0.10 (fixed in 20.0.10); from 21.0.0, before 21.0.2 (fixed in 21.0.2)

Published 2021-06-01. Last modified 2026-06-17.