Vulnerability CVE-2021-32727


Published: 2021-07-12

Description:
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.

Type:

CWE-295

(Certificate Issues)

CVSS2 => (AV:N/AC:L/Au:N/C:P/I:N/A:N)

CVSS Base Score
Impact Subscore
Exploitability Subscore
5/10
2.9/10
10/10
Exploit range
Attack complexity
Authentication
Remote
Low
No required
Confidentiality impact
Integrity impact
Availability impact
Partial
None
None
Affected software
Nextcloud -> Nextcloud 

 References:
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-5v33-r9cm-7736
https://github.com/nextcloud/android/pull/8438
https://github.com/nextcloud/end_to_end_encryption_rfc/blob/7f002996397faefb664019a97ebb0a1e210f64f0/RFC.md#further-devices
https://hackerone.com/reports/1189162

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