Fortinet FortiClient: Schwachstelle ermöglicht Denial of Service
WID-SEC-2026-3258 · first 09.09.2026 · updated 09.09.2026 · CVSS 5,1
What it is about
FortiClient ist ein Endgeräteschutz mit einem integrierten VPN-Client. Ein lokaler Angreifer kann eine Schwachstelle in Fortinet FortiClient ausnutzen, um einen Denial of Service Angriff durchzuführen.
Under what conditions?
Only with access to the device or an account on it. Often the second step after a phishing email.
What can happen in the worst case
An attacker could use the vulnerability to
- einen Denial of Service Angriff durchzuführen
Am I affected?
Affected according to the BSI:
- Fortinet FortiClient Windows <7.4.8
The installed version is usually shown under “Help → About” or in the device’s admin interface.
What helps?
Update to at least:
- Fortinet FortiClient Windows 7.4.8
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)
- FortiGuard Labs PSIRT Advisory FG-IR-26-165 vom 2026-09-08 www.fortiguard.com
CVE: CVE-2026-84386
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.