Nextcloud Flow: Schwachstelle ermöglicht Ausführen von beliebigem Programmcode mit Administratorrechten
WID-SEC-2026-0628 · first 06.03.2026 · updated 07.04.2026 · CVSS 9,8
What it is about
Nextcloud ist eine "on-premise" Plattform für Dateifreigabe und Zusammenarbeit. Ein Angreifer kann eine Schwachstelle in Nextcloud Flow ausnutzen, um beliebigen Programmcode mit Administratorrechten auszuführen.
Under what conditions?
The BSI does not name any particular preconditions. Exploitable remotely according to the BSI.
What can happen in the worst case
An attacker could use the vulnerability to
- beliebigen Programmcode mit Administratorrechten auszuführen
Am I affected?
Affected according to the BSI:
- Nextcloud Nextcloud Flow <1.3.0
The installed version is usually shown under “Help → About” or in the device’s admin interface.
What helps?
Update to at least:
- Nextcloud Nextcloud Flow 1.3.0
Is the vulnerability already being exploited?
None of the CVEs is in the CISA catalogue of exploited vulnerabilities. That does not mean there are no attacks, only that none are documented.
Information and sources
- Original BSI advisory (WID)
- NextCloud Security Advisory vom 2026-03-05 github.com
- Windfall exploit chain vom 2026-04-06 github.com
CVE: CVE-2026-29059
Source: BSI warning and information service (CERT-Bund); CISA. The assessment of the conditions is my reading of the BSI text; the external pages are in their original language.