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 products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| nextcloud | security-advisories | < 3.3.0 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | nextcloud-desktop | 3.3.1-1 | — |
| Debian 13 | nextcloud-desktop | 3.3.1-1 | — |
| Debian 12 | nextcloud-desktop | 3.3.1-1 | — |
| Debian 11 | nextcloud-desktop | 3.1.1-2+deb11u1 | DSA-4974-1 |
| Debian 10 | nextcloud-desktop | 2.5.1-3+deb10u2 | DSA-4974-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | nextcloud-desktop | No fix yet | — |
| Ubuntu 20.04 LTS | nextcloud-desktop | No fix yet | — |
Advisories 1
- DSA-4974-1 nextcloud-desktop - security update Debian Security (DSA / DLA) · Mar 9, 2026