Vulnerability Report

CVE-2021-32727

Title: End-to-End Encryption Private Key Validation Bypass

Data Exposure

Proof Of Concept

No public PoC currently indexed for CVE-2021-32727.

CWE Category CWE-295
Published Date Jul 12, 2021
Modified Date Nov 21, 2024
Exploit Status Not Found
Score 5.7 CVSS v3.1
Exploit Probability (EPSS)
0.73%

Vulnerability Summary

CVE-2021-32727: 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.

Impacted Vendors

N
nextcloud 1

Reference Links

https://github.com/nextcloud/android/pull/8438 https://github.com/nextcloud/end_to_end_encryption_rfc/blob/7f002996397faefb664019a97ebb0a1e210f64f0/RFC.md#further-devices https://github.com/nextcloud/security-advisories/security/advisories/GHSA-5v33-r9cm-7736 https://hackerone.com/reports/1189162 https://github.com/nextcloud/android/pull/8438 https://github.com/nextcloud/end_to_end_encryption_rfc/blob/7f002996397faefb664019a97ebb0a1e210f64f0/RFC.md#further-devices https://github.com/nextcloud/security-advisories/security/advisories/GHSA-5v33-r9cm-7736 https://hackerone.com/reports/1189162
CVSS v3.1
Source Entity [email protected]
Severity MEDIUM
5.7
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
REQUIRED
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
CVSS v3.1
Source Entity [email protected]
Severity HIGH
7.5
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS v2.0
Source Entity [email protected]
Severity MEDIUM
5.0
Access Vector
N/A
Authentication
N/A
RAW VECTOR AV:N/AC:L/Au:N/C:P/I:N/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2021-32727 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data or affected products updated.

PUBLISHED

Vulnerability first announced in NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity LOW
Privileges N/A
Interaction REQUIRED
CVSS Vector String CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N

Affected Stack

No specific products linked.