Applied Cybernetics Group
Threat intel → detection pipeline
Friday, September 18, 2026
Data as of 13:09 UTC

known ransomware use

Fortinet FortiOS and FortiProxy SSL-VPN Heap-Based Buffer Overflow Vulnerability

Added to KEV
2023-06-13
Federal due date
2023-07-04
Vendor
Fortinet
Product
FortiOS and FortiProxy SSL-VPN
EPSS
99.7th percentile (score 0.857, as of 2026-09-16)
NVD CVSS v3.1
9.8 (CRITICAL)
Ransomware use
Known
ATT&CK
T1136 , T1190 , T1574 · signal rollup
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2023-27997

CISA short description

Fortinet FortiOS and FortiProxy SSL-VPN contain a heap-based buffer overflow vulnerability which can allow an unauthenticated, remote attacker to execute code or commands via specifically crafted requests.

Required action

Apply updates per vendor instructions.

NVD description

A heap-based buffer overflow vulnerability [CWE-122] in FortiOS version 7.2.4 and below, version 7.0.11 and below, version 6.4.12 and below, version 6.0.16 and below and FortiProxy version 7.2.3 and below, version 7.0.9 and below, version 2.0.12 and below, version 1.2 all versions, version 1.1 all versions SSL-VPN may allow a remote attacker to execute arbitrary code or commands via specifically crafted requests.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.