// For flags

CVE-2021-32727

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

Severity Score

7.5
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

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.

Nextcloud Android Client es el cliente Android para Nextcloud. Unos clientes que usan la funcionalidad end-to-end encryption de Nextcloud descargan la clave pública y privada por medio de un endpoint de la API. En versiones anteriores a 3.16.1, el cliente Android de Nextcloud se saltaba un paso que implicaba que el cliente comprobara si una clave privada pertenecía a un certificado público previamente descargado. Si la instancia de Nextcloud servía una clave pública maliciosa, los datos estarían cifrados para esta clave y, por tanto, podrían ser accesibles para un actor malicioso. La vulnerabilidad está parcheada en la versión 3.16.1. Como solución alternativa, no añada dispositivos cifrados de extremo a extremo adicionales a una cuenta de usuario

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None
Attack Vector
Network
Attack Complexity
Low
Authentication
None
Confidentiality
Partial
Integrity
None
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2021-05-12 CVE Reserved
  • 2021-07-12 CVE Published
  • 2024-03-27 EPSS Updated
  • 2024-08-03 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-295: Improper Certificate Validation
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Nextcloud
Search vendor "Nextcloud"
 Nextcloud
Search vendor "Nextcloud" for product "Nextcloud"
 < 3.16.1
Search vendor "Nextcloud" for product "Nextcloud" and version " < 3.16.1"
android
Affected