Description
The Nextcloud Desktop Client is a tool to synchronize files from Nextcloud Server with a computer. Clients using the Nextcloud end-to-end encryption feature download the public and private key via an API endpoint. In versions prior to 3.3.0, the Nextcloud Desktop client fails to check if a private key belongs to previously downloaded public certificate. If the Nextcloud instance serves a malicious public key, the data would be encrypted for this key and thus could be accessible to a malicious actor. This issue is fixed in Nextcloud Desktop Client version 3.3.0. There are no known workarounds aside from upgrading.
References (4)
Core 4
Core References
Exploit, Third Party Advisory x_refsource_misc
https://hackerone.com/reports/1189162
Exploit, Third Party Advisory x_refsource_confirm
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-f5fr-5gcv-6cc5
Patch, Third Party Advisory x_refsource_misc
https://github.com/nextcloud/desktop/pull/3338
Third Party Advisory vendor-advisory
x_refsource_debian
https://www.debian.org/security/2021/dsa-4974
Scores
CVSS v3
6.5
EPSS
0.0021
EPSS Percentile
43.1%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Details
CWE
CWE-295
Status
published
Products (3)
debian/debian_linux
10.0
debian/debian_linux
11.0
nextcloud/desktop
< 3.3.0
Published
Aug 18, 2021
Tracked Since
Feb 18, 2026