Proxmox Backup Server: Schwachstelle ermöglicht Manipulation von Dateien und Offenlegung von Informationen
WID-SEC-2026-2838 · first 14.08.2026 · updated 14.08.2026 · CVSS 9,1
What it is about
Proxmox Backup Server ist eine Enterprise-Backup-Lösung zur Sicherung und Wiederherstellung von VMs, Containern und physischen Hosts. Ein Angreifer kann eine Schwachstelle in Proxmox Backup Server ausnutzen, um Dateien zu manipulieren, und um Informationen offenzulegen.
Under what conditions?
Only with direct access to the device, for example via USB or on site. Exploitable remotely according to the BSI.
What can happen in the worst case
An attacker could use the vulnerability to
- Dateien zu manipulieren
- Informationen offenzulegen
Am I affected?
Affected according to the BSI:
- Proxmox Backup Server <4.2.5-1
- Proxmox Backup Server <3.4.9-1
The installed version is usually shown under “Help → About” or in the device’s admin interface.
What helps?
Update to at least:
- Proxmox Backup Server 4.2.5-1
- Proxmox Backup Server 3.4.9-1
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)
- Proxmox Security Advisory vom 2026-08-13 forum.proxmox.com
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.