CVE-2021-32727
mediumpriority · track · 30EPSS 0.007 · 54 %ileEUUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (3)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- BIT-nextcloud-2021-32727End-to-end encryption device setup did not verify public key2026-07-12vendor · osvUS
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.
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (14)
External citations — patches, advisories, analysis.
- https://github.com/nextcloud/android/pull/8438cnnvd
- https://github.com/nextcloud/end_to_end_encryption_rfc/blob/7f002996397faefb664019a97ebb0a1e210f64f0/RFC.md#further-devicescnnvd
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-5v33-r9cm-7736cnnvd
- https://hackerone.com/reports/1189162cnnvd
- https://nvd.nist.gov/vuln/detail/CVE-2021-32727cnnvd
- https://www.cybersecurity-help.cz/vdb/SB2021071215cnnvd
- https://github.com/nextcloud/android/pull/8438enisa_euvd
- https://github.com/nextcloud/end_to_end_encryption_rfc/blob/7f002996397faefb664019a97ebb0a1e210f64f0/RFC.md#further-devicesenisa_euvd
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