CVE-2021-32727 json
End-to-end encryption device setup did not verify public key
published 2021-07-12 5 y ago modified 2026-09-08 2 mo ago also BIT-nextcloud-2021-32727 , EUVD-2021-19509 , GHSA-5v33-r9cm-7736
- cvss
- 5.7
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 54%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
Exploit prediction
0.73% chance of exploitation in the next 30 days, higher than 54% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N |
| NVD | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
| NVD | 2.0 | 5.0 | AV:N/AC:L/Au:N/C:P/I:N/A:N |
| OSV | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| bitnami | nextcloud | <3.16.1 |
3.16.1 |
Affected products
- nextcloud security-advisories
Classification
- Weakness
-
- CWE-295 Improper Certificate Validation
References
-
github.com
/nextcloud/android/pull/8438
third-party-advisory, advisory
-
github.com
/nextcloud/security-advisories/security/advisories/GHSA-5v33-r9cm-7736
third-party-advisory, advisory
-
hackerone.com
/reports/1189162
permissions-required, web
-
github.com
/nextcloud/end_to_end_encryption_rfc/blob/7f002996397faefb664019a97ebb0a1e210f64f0/RFC.md#further-devices
third-party-advisory, advisory
-
nvd.nist.gov
/vuln/detail/CVE-2021-32727
web
Sources
- CVE List CVE-2021-32727
- NVD CVE-2021-32727
- OSV BIT-nextcloud-2021-32727
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