November 3, 2021 · Applied Cybernetics Group
CVE-2019-5591 — Fortinet FortiOS
known ransomware use
Fortinet FortiOS Default Configuration Vulnerability
- Added to KEV
2021-11-03- Federal due date
2022-05-03- Vendor
- Fortinet
- Product
- FortiOS
- EPSS
- 97.1th percentile (score 0.184, as of
2026-09-16) - NVD CVSS v3.1
- 6.5 (MEDIUM)
- Ransomware use
- Known
- ATT&CK
- T1005 , T1133 , T1557 · signal rollup
- Upstream
- https://nvd.nist.gov/vuln/detail/CVE-2019-5591
CISA short description
Fortinet FortiOS contains a default configuration vulnerability that may allow an unauthenticated attacker on the same subnet to intercept sensitive information by impersonating the Lightweight Directory Access Protocol (LDAP) server.
Required action
Apply updates per vendor instructions.
NVD description
A Default Configuration vulnerability in FortiOS may allow an unauthenticated attacker on the same subnet to intercept sensitive information by impersonating the LDAP server.