Buffer underflow in FortiOS - CVE-2025-53843
Published: November 18, 2025
Vulnerability identifier: #VU118602
CSH Severity: Low
CVSS v4.0: 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/E:U/U:Clear
CVE-ID: CVE-2025-53843
CWE-ID: CWE-124
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Fortinet, Inc
Affected software:
FortiOS
FortiOS
Detailed vulnerability description
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.
How to mitigate CVE-2025-53843
Install update from vendor's website.