---
id: "CVE-2019-5591"
kind: "vulnerability"
aliases: ["CVE-2019-5591"]
title: "Fortinet FortiOS: Fortinet FortiOS Default Configuration Vulnerability"
severity: "high"
cvss: 6.5
epss: 0.18566
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "Fortinet FortiOS", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "firewall", "fortinet", "fortios", "infrastructure", "ldap", "ransomware"]
not_affected_if: ["no-ldap-integration", "not-on-same-subnet"]
published_at: "2020-08-14T16:15:16+00:00"
first_seen_at: "2026-10-23T19:11:53+00:00"
updated_at: "2026-10-23T21:57:35+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2019-5591", "first_seen_at": "2026-10-23T19:11:53+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2019-5591", "first_seen_at": "2026-10-23T19:13:44+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2019-5591", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Fortinet FortiOS: Fortinet FortiOS Default Configuration Vulnerability

Fortinet FortiOS ships with a default configuration that lets an unauthenticated attacker on the same subnet impersonate the LDAP server. The attacker can intercept sensitive information such as LDAP credentials sent by the device.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Fortinet FortiOS affected ? fixed ?

## Fix

Apply updates per vendor instructions (CISA KEV required action); the specific fixed FortiOS version and the setting to change are unknown from the sources.

## Timeline

- 2026-10-23T19:11:53+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2019-5591
- 2026-10-23T19:13:44+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2019-5591
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2019-5591

## From the sources

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.

CISA required action: Apply updates per vendor instructions.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_