CVE-2021-32727

Name: CVE-2021-32727
Creator: NVD / NIST
Published: 2021-07-12T21:15:07.817+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.73%

Last modified Jun 17, 2026

CVE-2021-32727 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.73% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

0.73%

49.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Nextcloud	Nextcloud	< 3.16.1

References

https://github.com/nextcloud/android/pull/8438Third Party Advisory
https://github.com/nextcloud/end_to_end_encryption_rfc/blob/7f002996397faefb664019a97ebb0a1e210f64f0/RFC.md#further-devicesThird Party Advisory
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-5v33-r9cm-7736Third Party Advisory
https://hackerone.com/reports/1189162Permissions Required
https://github.com/nextcloud/android/pull/8438Third Party Advisory
https://github.com/nextcloud/end_to_end_encryption_rfc/blob/7f002996397faefb664019a97ebb0a1e210f64f0/RFC.md#further-devicesThird Party Advisory
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-5v33-r9cm-7736Third Party Advisory
https://hackerone.com/reports/1189162Permissions Required

Timeline

Published: Jul 12, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-32727?

How severe is CVE-2021-32727?

CVE-2021-32727 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.73% probability of exploitation in the next 30 days.

How do I fix CVE-2021-32727?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-32727?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST