Improper certificate validation in FortiOS - CVE-2026-121528
Published: November 11, 2026
Vulnerability identifier: #VU165149
CSH Severity: High
CVSS v4: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-121528
CWE-ID: CWE-295
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote non-authenticated attacker to execute arbitrary code.
The vulnerability exists due to improper certificate validation. A remote and unauthenticated attacker can perform a Man-in-the-Middle attack on the communication channel between the SSLVPN web portal and the backend destination website.
Affected software
FortiOS
How to mitigate CVE-2026-121528
Install update from vendor's website.
FortiOS - addressed in versions 7.2.14, 7.4.10, 7.6.5