CVE-2021-37617: Nextcloud Desktop

High severity, CVSS 7.3. EPSS: 0.5% chance of exploitation in the next 30 days.

The Nextcloud Desktop Client is a tool to synchronize files from Nextcloud Server with a computer. The Nextcloud Desktop Client invokes its uninstaller script when being installed to make sure there are no remnants of previous installations. In versions 3.0.3 through 3.2.4, the Client searches the `Uninstall.exe` file in a folder that can be written by regular users. This could lead to a case where a malicious user creates a malicious `Uninstall.exe`, which would be executed with administrative privileges on the Nextcloud Desktop Client installation. This issue is fixed in Nextcloud Desktop Client version 3.3.0. As a workaround, do not allow untrusted users to create content in the `C:\` system folder and verify that there is no malicious `C:\Uninstall.exe` file on the system.

Affected products

• Nextcloud Desktop: from 3.0.3, before 3.3.0 (fixed in 3.3.0)

Published 2021-08-18. Last modified 2026-06-17.