Vulnerability Monitor

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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.

Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 6.5, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction requiring only low-level privileges . The vulnerability impacts confidentiality (data exposure), for affected systems. Impacting 2 products from nextcloud, from debian organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.

Published

2021-08-18T16:15:07.293

Last Modified

2024-11-21T06:07:36.810

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 6.5 (MEDIUM)

CVSSv2 Vector

AV:N/AC:L/Au:S/C:P/I:N/A:N

Access Vector: NETWORK
Access Complexity: LOW
Authentication: SINGLE
Confidentiality Impact: PARTIAL
Integrity Impact: NONE
Availability Impact: NONE

Exploitability Score

8.0

Impact Score

2.9

Weaknesses

Type: Secondary
CWE-295

Affected Vendors & Products

Type	Vendor	Product	Version/Range	Vulnerable?
Application	nextcloud	desktop	< 3.3.0	Yes
Operating System	debian	debian_linux	10.0	Yes
Operating System	debian	debian_linux	11.0	Yes

References

https://github.com/nextcloud/desktop/pull/3338 Patch, Third Party Advisory ([email protected])
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-f5fr-5gcv-6cc5 Exploit, Third Party Advisory ([email protected])
https://hackerone.com/reports/1189162 Exploit, Third Party Advisory ([email protected])
https://www.debian.org/security/2021/dsa-4974 Third Party Advisory ([email protected])
https://github.com/nextcloud/desktop/pull/3338 Patch, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-f5fr-5gcv-6cc5 Exploit, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://hackerone.com/reports/1189162 Exploit, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.debian.org/security/2021/dsa-4974 Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For nextcloud's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.