CVE-2021-37617

low-risk
Published 2021-08-18

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.

Do I need to act?

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0.39% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
7
CVSS 7.3/10 High
LOCAL / LOW complexity

Affected Products (1)

Affected Vendors

Nextcloud

References (6)

Patch https://github.com/nextcloud/desktop/pull/3497
Third Party Advisory https://github.com/nextcloud/security-advisories/security/advisories/GHSA-6q2w-v...
Permissions Required https://hackerone.com/reports/1240749
Patch https://github.com/nextcloud/desktop/pull/3497
Third Party Advisory https://github.com/nextcloud/security-advisories/security/advisories/GHSA-6q2w-v...
Permissions Required https://hackerone.com/reports/1240749
29
/ 100
low-risk
Severity 23/34 · High
Exploitability 1/34 · Minimal
Exposure 5/34 · Minimal