CVE-2021-32727

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

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.

Category

5.7
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.17%
Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory github.com
Affected: nextcloud security-advisories
Published at:
Updated at:

References

Link Tags
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-5v33-r9cm-7736 third party advisory
https://github.com/nextcloud/android/pull/8438 third party advisory
https://hackerone.com/reports/1189162 permissions required
https://github.com/nextcloud/end_to_end_encryption_rfc/blob/7f002996397faefb664019a97ebb0a1e210f64f0/RFC.md#further-devices third party advisory

Frequently Asked Questions

What is the severity of CVE-2021-32727?
CVE-2021-32727 has been scored as a medium severity vulnerability.
How to fix CVE-2021-32727?
To fix CVE-2021-32727, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-32727 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-32727 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-32727?
CVE-2021-32727 affects nextcloud security-advisories.
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