Buffer underflow in FortiOS - CVE-2025-53843
Published: November 18, 2025
Vulnerability identifier: #VU118602
CSH Severity: Low
CVSS v4: 7.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2025-53843
CWE-ID: CWE-124
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote authenticated user to execute arbitrary code.
The vulnerability exists due to buffer underwrite ('buffer underflow') in CAPWAP daemon. A remote authenticated attacker can execute arbitrary code or command as a low privileged user via specially crafted packets.Successful exploitation would require a large amount of effort in preparation because of stack protection and ASLR. Additionally, attacker must be able to pose as an authorized FortiAP or FortiExtender.
Affected software
FortiOS
How to mitigate CVE-2025-53843
Install update from vendor's website.
FortiOS - addressed in versions 7.4.9, 7.6.4