Vulnerability · Published Aug 18, 2021 · Assigned by GitHub_M
CVE-2021-32728End-to-end encryption device setup did not verify public key
Medium 6.5
In plain English
A medium-severity improper certificate validation in security-advisories from nextcloud. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.9% (higher than 58% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
The Nextcloud Desktop Client is a tool to synchronize files from Nextcloud Server with a computer. Clients using the Nextcloud end-to-end encryption feature download the public and private key via an API endpoint. In versions prior to 3.3.0, the Nextcloud Desktop client fails to check if a private key belongs to previously downloaded public certificate. If the Nextcloud instance serves a malicious public key, the data would be encrypted for this key and thus could be accessible to a malicious actor. This issue is fixed in Nextcloud Desktop Client version 3.3.0. There are no known workarounds aside from upgrading.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | nextcloud-desktop | 3.3.1-1 | DEBIAN-CVE-2021-32728 |
| Debian:13 | nextcloud-desktop | 3.3.1-1 | DEBIAN-CVE-2021-32728 |
| Debian:14 | nextcloud-desktop | 3.3.1-1 | DEBIAN-CVE-2021-32728 |
| Ubuntu:22.04:LTS | nextcloud-desktop | no fix listed | UBUNTU-CVE-2021-32728 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| nextcloud | security-advisories | < 3.3.0 |
Weakness: CWE-295 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
References
- https://hackerone.com/reports/1189162 x_refsource_MISC
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-f5fr-5gcv-6cc5 x_refsource_CONFIRM
- https://github.com/nextcloud/desktop/pull/3338 x_refsource_MISC
- DSA-4974 vendor-advisory, x_refsource_DEBIAN