CVE-2021-32728 End-to-end encryption device setup did not verify public key

2021-08-1816:00:13

CWE-295

GitHub_M

www.cve.org

cve-2021-32728

end-to-end encryption

nextcloud desktop client

public key

private key

api endpoint

malicious actor

security fix

upgrade

CVSS3

6.5

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

NONE

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

AI Score

6.4

Confidence

High

EPSS

0.009

Percentile

82.6%

JSON

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.

CNA Affected

[
  {
    "product": "security-advisories",
    "vendor": "nextcloud",
    "versions": [
      {
        "status": "affected",
        "version": "< 3.3.0"
      }
    ]
  }
]