Vulnerability in Nextcloud Desktop
CVE-2021-32728
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.
Vulnerability class: Improper Certificate Validation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.009 (56.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 57th percentile — 56.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000
Affected products
- Nextcloud Desktop
- Nextcloud Security-Advisories — versions < 3.3.0
- Debian Linux — versions 10.0, 11.0
Weakness classification (CWE)
References
- hackerone.com/reports/1189162 (Exploit, Third Party Advisory)
- github.com/nextcloud/security-advisories/security/advisories/GHSA-f5fr-5gcv-6cc5 (Exploit, Third Party Advisory)
- github.com/nextcloud/desktop/pull/3338 (Patch, Third Party Advisory)
- www.debian.org/security/2021/dsa-4974 (vendor-advisory, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-32728?
- CVE-2021-32728 is a medium-severity vulnerability in Nextcloud Desktop, classified under Improper Certificate Validation. CVSS score: 6.5/10. Published 2021-08-18.
- How severe is CVE-2021-32728?
- Medium severity. CVSS v3 base score is 6.5 out of 10.