Stack-based buffer overflow in FortiAuthenticator - CVE-2026-126239
Published: November 11, 2026
Vulnerability identifier: #VU165115
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-126239
CWE-ID: CWE-121
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote non-authenticated attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to stack-based buffer overflow. An unauthenticated attacker can crash the FSSO subsystem via crafted http requests.
Affected software
FortiAuthenticator
How to mitigate CVE-2026-126239
Install update from vendor's website.
FortiAuthenticator - addressed in versions 6.6.11, 8.0.4