Fortinet FortiOS and FortiADC LDAP Credential Exposure Vulnerability (CVE-2018-13374) Analysis and Mitigation Guide
Executive & SecOps Summary
SECOPS ASSESSMENTEnterprise network environments running FortiOS 6.0.2, 5.6.7 and before, or FortiADC 6.1.0, 6.0.0 to 6.0.1, 5.4.0 to 5.4.4
An authenticated attacker can redirect LDAP connectivity test requests to a rogue LDAP server, exposing configured LDAP administrator credentials in plaintext or reversible format
Upgrade FortiOS and FortiADC to the latest patched versions immediately and restrict administrative access using trusted host configurations
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Apply the official security patches by upgrading your FortiOS/FortiADC firmware to a non-vulnerable version. Verify the current version and perform the upgrade via CLI.
# Check current FortiOS version
get system status
# Example: Upgrade firmware via TFTP server (Recommended to upgrade to FortiOS 6.0.3 or higher)
execute restore image tftp FGT_60-v6-build1639-FORTINET.out 192.168.1.992. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, restrict administrative access to trusted IP addresses to minimize the attack surface.
# Restrict administrator access to trusted subnets only
config system admin
edit 'admin'
set trusthost1 10.10.10.0 255.255.255.0
set trusthost2 192.168.10.0 255.255.255.0
next
end3. Log Audit & IoC Verification Commands
Audit system logs for unauthorized LDAP configuration changes or outbound LDAP connections (TCP ports 389/636) to unrecognized external IP addresses.
# Filter and display logs related to LDAP configurations
show log syslog filter
execute log filter category 1
execute log filter field msg 'LDAP'
execute log displayStop Exposing VPN Ports to the Internet — Switch to Zero-Trust Access
Eliminate public-facing VPN concentrators and firewall management ports with identity-first Zero-Trust Network Access.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2018-13374) stems from improper access control (CWE-732) within the LDAP configuration utility of Fortinet FortiOS and FortiADC. The administrative interface provides an 'LDAP connectivity test' feature to verify communication with the configured directory server. However, a design flaw allows the destination server address parameter to be manipulated without proper validation.
2. Exploitation Mechanics & Attack Scenario
An attacker with low-privileged administrative access can intercept or craft a malicious LDAP connectivity test request. By modifying the target server parameter to point to an attacker-controlled rogue LDAP server, the attacker forces the FortiGate/FortiADC appliance to initiate an LDAP Bind request to the rogue server. During this handshake, the appliance transmits the configured LDAP Bind DN credentials, allowing the attacker to capture them.
3. Infrastructure & Business Impact
Compromising LDAP credentials grants attackers direct access to the organization's Active Directory (AD) or LDAP directory services. This exposure can lead to unauthorized access to sensitive employee data, system accounts, and facilitates lateral movement across the internal corporate network, posing a severe threat to overall business operations.
Official Vendor Advisories & References
A Improper Access Control in Fortinet FortiOS 6.0.2, 5.6.7 and before, FortiADC 6.1.0, 6.0.0 to 6.0.1, 5.4.0 to 5.4.4 allows attacker to obtain the LDAP server login credentials configured in FortiGate via pointing a LDAP server connectivity test request to a rogue LDAP server instead of the configured one.
Frequently Asked SecOps Questions (CVE-2018-13374)
FAQQ1. How critical is CVE-2018-13374 and is it actively exploited in the wild?
CVE-2018-13374 is rated CVSS 4.3 (MEDIUM) with a 30-day EPSS exploitation probability of 38.1%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2018-13374?
Primary impacted vendors include fortinet across fortios, fortiadc. Scope summary: FortiOS 6.0.2 and before, 5.6.7 and before / FortiADC 6.1.0, 6.0.0 to 6.0.1, 5.4.0 to 5.4.4
Q3. What temporary mitigations or workarounds exist for CVE-2018-13374 before patching?
[Mitigation] Upgrade FortiOS and FortiADC to the latest patched versions immediately and restrict administrative access using trusted host configurations Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2018-13374
Instantly format this advisory into an executive CISO summary or engineering patch ticket.
🔗 Related Advisories in Similar Stack (fortinet)
View Category →Fortinet FortiOS/FortiProxy Path Traversal Vulnerability Advisory (CVE-2025-61624)
[Affected Scope] Major Fortinet solutions including FortiOS (6.4-7.6), FortiPAM (1.0-1.7), FortiProxy (7.0-7.6), and FortiSwitchManager (7.0-7.2).
Fortinet FortiOS Sensitive Information Exposure and Symbolic Link Patch Bypass (CVE-2025-68686)
[Affected Scope] Fortinet FortiOS versions 7.6.0 through 7.6.1, 7.4.0 through 7.4.6, and all versions of 7.2, 7.0, and 6.4
Fortinet FortiMail Path Traversal Vulnerability (CVE-2026-104286) - Unauthenticated Arbitrary File Write
[Affected Scope] FortiMail versions 8.0.0-8.0.1, 7.6.0-7.6.6, 7.4.0-7.4.8, 7.2.0-7.2.9, and all 7.0 versions.
Fortinet FortiSandbox OS Command Injection Vulnerability (CVE-2026-25089) Security Advisory
[Affected Scope] Fortinet FortiSandbox (5.0.0 to 5.0.5, 4.4.0 to 4.4.8, 4.2 all versions), FortiSandbox Cloud and PaaS (5.0.4 to 5.0.5)
Subscribe to Daily Vulnerability Briefings & KEV Alerts
Concise morning briefings for SecOps, DevSecOps, and SRE teams covering newly exploited CVEs and mitigation priorities.