CVE-2021-32727

End-to-end encryption device setup did not verify public key

HIGH
7.5
CVSS Score
Published: July 12, 2021 at 08:40 PM UTC
Updated: June 17, 2026 at 03:53 AM UTC
1 product affected across 1 vendorNextcloud/server

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Severity
HIGH7.5
Exploit prediction
EPSS 0.7%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.16.1
Affected range stops below 3.16.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-295

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