Fortinet FortiOS CVE-2018-13379
CRITICALVulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2021 - Broken Access Control
ASVS 5.0
V4 - Access Control Authorization enforcement, RBAC validation
MITRE ATT&CK
2 techniques across 2 tactics: Discovery, Collection The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | Critical risk (CVSS 9.1, EPSS 94.5%). One of the most exploited VPN vulnerabilities in history. Credentials harvested through this flaw were used by APT groups (APT5, Volt Typhoon), ransomware gangs (Conti, LockBit), and initial access brokers. Lists of vulnerable IPs with extracted credentials were traded on dark web forums. |
| Exploit ScenarioDerived | Attackers scan for Fortinet VPN portals, exploit the path traversal to extract the sslvpn_websession file containing plaintext VPN credentials. Using these credentials, they establish VPN access to the corporate network, move laterally, and deploy ransomware or conduct espionage. |
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Alert meAnalysisAIv1 – Mar 26, 2026
Fortinet FortiOS SSL-VPN contains a path traversal vulnerability allowing unauthenticated attackers to download system files including session tokens and credentials, massively exploited from 2019 onward by APT and ransomware groups.
Earlier versions of this analysis (1)
A path traversal vulnerability in Fortinet FortiOS and FortiProxy SSL-VPN web portal allows unauthenticated attackers to read arbitrary system files through crafted HTTP requests, including plaintext credentials and session tokens.
RemediationAI
Upgrade FortiOS immediately. Rotate ALL VPN user credentials after patching. Enable MFA for VPN access. Check for unauthorized access using harvested credentials in authentication logs.
Affected ProductsAI
Fortinet FortiOS 6.0.0 to 6.0.4 Fortinet FortiOS 5.6.3 to 5.6.7 Fortinet FortiOS 5.4.6 to 5.4.12 Fortinet FortiProxy 2.0.0 Fortinet FortiProxy 1.2.0 to 1.2.8 Fortinet FortiProxy 1.1.0 to 1.1.6 Fortinet FortiProxy 1.0.0 to 1.0.7
Affects your stack
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Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
The CWE-22 path traversal in the SSL-VPN web portal allows accessing files outside the intended directory. The critical impact comes from the ability to read /dev/cmdb/sslvpn_websession, which contains plaintext usernames and passwords for VPN sessions, enabling immediate account compromise.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
Lifecycle Timeline
3DescriptionCVE.org
An Improper Limitation of a Pathname to a Restricted Directory ("Path Traversal") in Fortinet FortiOS 6.0.0 to 6.0.4, 5.6.3 to 5.6.7 and 5.4.6 to 5.4.12 and FortiProxy 2.0.0, 1.2.0 to 1.2.8, 1.1.0 to 1.1.6, 1.0.0 to 1.0.7 under SSL VPN web portal allows an unauthenticated attacker to download system files via special crafted HTTP resource requests.
Executive ViewAI
CVE-2018-13379 presents critical security risk, a path traversal vulnerability rated CVSS 9.1. This could allow attackers to access or modify files outside intended directories, potentially exposing sensitive configuration or credentials. This vulnerability is actively exploited in the wild (KEV-listed) and requires immediate remediation. Immediate patching is required per CISA KEV mandate.
Apply vendor patch. If immediate patching is not feasible: (1) Restrict file upload functionality via WAF; (2) Implement allowlist-based file type validation; (3) Use chroot/containerization to limit filesystem access.
Threat Intelligence Overview
NVD
CVE.org
CISA KEV
EPSS
Exploit-DB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
GitHub PoC