CVE-2021-32728
End-to-end encryption device setup did not verify public key
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
End-to-end encryption device setup did not verify public key
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.
- Record
CVE-2021-32728- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-295
- Updated
- 2026-11-02
EUVDEUVD-2021-19510
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.
- Record
EUVD-2021-19510- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-03
NVD
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.
- Record
CVE-2021-32728- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N - CVSS 2.0
- 4.0 Medium
AV:N/AC:L/Au:S/C:P/I:N/A:N - Weakness
- CWE-295
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2021-32728- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
OSVDEBIAN-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.
- Record
DEBIAN-CVE-2021-32728- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
OSVUBUNTU-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.
- Record
UBUNTU-CVE-2021-32728- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
OSVMGASA-2021-0421 No score
Updated nextcloud-client packages fix security vulnerability
Nextcloud Desktop Client before 3.3.1 is vulnerable to improper certificate validation due to lack of SSL certificate verification when using the "Register with a Provider" flow. (CVE-2021-22895)
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
- Record
MGASA-2021-0421- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
nextcloud-desktopDebian:12 |
before 3.3.1-1 | 3.3.1-1 |
nextcloud-desktopDebian:13 |
before 3.3.1-1 | 3.3.1-1 |
nextcloud-desktopDebian:14 |
before 3.3.1-1 | 3.3.1-1 |
nextcloud-desktopDebian:10 |
before 2.5.1-3+deb10u2, plus listed versions 2.5.1-32.5.1-3+deb10u1 |
2.5.1-3+deb10u2 |
nextcloud-desktopDebian:11 |
before 3.1.1-2+deb11u1, plus listed versions 3.1.1-2 |
3.1.1-2+deb11u1 |
nextcloud-clientMageia:8 |
before 3.3.3-1.mga8 | 3.3.3-1.mga8 |
nextcloud-desktopUbuntu:20.04:LTS |
All versions, plus listed versions 2.5.3-12.6.0-12.6.1-12.6.1-22.6.2-12.6.2-1build1 |
None known |
nextcloud-desktopUbuntu:22.04:LTS |
All versions, plus listed versions 3.2.3-0ubuntu13.3.5-13.3.5-1ubuntu13.4.2-13.4.2-1ubuntu1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, products | EUVD | |
| first indexed | CVE List, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-32728 is a medium vulnerability (CVSS 6.5) in Nextcloud Desktop, published August 18, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.85%, the 58th percentile. Fixed in nextcloud-desktop 3.3.1-1.