Vulnerability in Nextcloud
CVE-2021-32727
Nextcloud Android Client is the Android client for Nextcloud. Clients using the Nextcloud end-to-end encryption feature download the public and private key via an API endpoint. In versions prior to 3.16.1, the Nextcloud Android client skipped a step that involved the client checking if a private key belonged to a previously downloaded public certificate. If the Nextcloud instance served a malicious public key, the data would be encrypted for this key and thus could be accessible to a malicious actor. The vulnerability is patched in version 3.16.1. As a workaround, do not add additional end-to-end encrypted devices to a user account.
Vulnerability class: Improper Certificate Validation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.007 (52.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 52.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000
Affected products
- Nextcloud
- Nextcloud Security-Advisories — versions < 3.16.1
Weakness classification (CWE)
References
- github.com/nextcloud/security-advisories/security/advisories/GHSA-5v33-r9cm-7736 (Third Party Advisory)
- github.com/nextcloud/android/pull/8438 (Third Party Advisory)
- hackerone.com/reports/1189162 (Permissions Required)
- github.com/nextcloud/end_to_end_encryption_rfc/blob/7f002996397faefb664019a97eb… (Third Party Advisory)
Frequently asked questions
- What is CVE-2021-32727?
- CVE-2021-32727 is a medium-severity vulnerability in Nextcloud, classified under Improper Certificate Validation. CVSS score: 5.7/10. Published 2021-07-12.
- How severe is CVE-2021-32727?
- Medium severity. CVSS v3 base score is 5.7 out of 10.