CVE-2021-32728

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

MEDIUM
6.5
CVSS Score
Published: August 18, 2021 at 04:00 PM UTC
Updated: June 17, 2026 at 03:53 AM UTC
2 products affected across 2 vendorsDebian LinuxDesktop

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.9%

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.

Affected

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

Desktop· Nextcloudnextcloud-app
95%
v < 3.3.0
Affected range stops below 3.3.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

x_refsource_MISCPatchThird Party Advisory
https://github.com/nextcloud/desktop/pull/3338
x_refsource_MISCExploitThird Party Advisory
https://hackerone.com/reports/1189162
Vendor Advisoryx_refsource_DEBIANThird Party Advisory
https://www.debian.org/security/2021/dsa-4974

CVSS

6.5MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-295

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