CVE-2018-13379: Fortinet FortiOS SSL VPN Path Traversal Vulnerability
Fortinet · FortiOS · NVD published 2019-06-05 · posted 2026-10-21 · last modified 2026-06-17
What it is
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.
| Weakness | CWE-22 |
|---|---|
| CVSS vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (source: [email protected]) |
| CISA due date | 2022-05-03 (for US federal agencies under BOD; a good deadline for everyone) |
| ATT&CK tactics | Initial Access |
Exploitation evidence
First exploit evidence seen: 2019-08-11 (earliest date across the sources below).
Exploited in the wild
- CISA KEV: listed since 2021-11-03. Source
Public exploit code
Metasploit
auxiliary/gather/fortios_vpnssl_traversal_creds_leak: FortiOS Path Traversal Credential Gatherer
Exploit-DB
- EDB-47288: Fortinet FortiOS 5.6.3 - 5.6.7 / FortiOS 6.0.0 - 6.0.4 - Credentials Disclosure (2019-08-19)
- EDB-47287: Fortinet FortiOS 5.6.3 - 5.6.7 / FortiOS 6.0.0 - 6.0.4 - Credentials Disclosure (Metasploit) (2019-08-19)
GitHub proof-of-concept repositories
14 public repositories from 14 accounts, first seen 2019-08-11. Most starred: milo2012/CVE-2018-13379 (253 stars), view repository.
Verify before running: public PoCs can be malicious. Read the code and only run it in an isolated lab. A PoC means exploit code is public, not that this CVE is exploited in the wild.
Sources: CISA KEV · Rapid7 Metasploit Framework module metadata · Exploit-DB (OffSec) · nomi-sec/PoC-in-GitHub.
Defend the Chain
The attack chain for CVE-2018-13379 laid across the MITRE ATT&CK Enterprise tactics. Solid cards come from the MITRE CTID KEV mappings; dashed cards are inferred by CVERadar from the CWE or description. Correct defences are real ATT&CK mitigations for that technique.
Pick a red technique card on the board, then choose the defence that stops it.
Defend against T1190 Exploit Public-Facing Application CTID: exploitation technique
This is a path traversal vulnerability that allows adversary to download system files through specially-crafted HTTP requests.
How to fix it
CISA required action
Apply updates per vendor instructions. (source: CISA KEV)
Fixed versions
- fortinet fortiproxy: upgrade to 1.2.9 or later
- fortinet fortios: upgrade to 5.4.13 or later (affected from 5.4.6)
- fortinet fortios: upgrade to 5.6.8 or later (affected from 5.6.3)
- fortinet fortios: upgrade to 6.0.5 or later (affected from 6.0.0)
Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.
Vendor advisories and patches
- https://fortiguard.com/advisory/FG-IR-18-384 (Mitigation, Vendor Advisory)
- https://www.fortiguard.com/psirt/FG-IR-20-233 (Vendor Advisory)
MITRE ATT&CK mitigations for this chain
- M1048 Application Isolation and Sandboxing (for T1190) : Application isolation will limit what other processes and system features the exploited target can access.
- M1037 Filter Network Traffic (for T1190) : Restrict outbound network traffic from public-facing servers to prevent unauthorized connections from initiating communications with attacker-controlled infrastructure. While this may not prevent the initial exploitation, it limits the attacker's ability to verify and control the compromised server post-exploit, reduci
- M1030 Network Segmentation (for T1190) : Segment externally facing servers and services from the rest of the network with a DMZ or on separate hosting infrastructure.
- M1016 Vulnerability Scanning (for T1190) : Regularly scan externally facing systems for vulnerabilities and establish procedures to rapidly patch systems when critical vulnerabilities are discovered through scanning and through public disclosure.
- M1026 Privileged Account Management (for T1190) : Use least privilege for service accounts will limit what permissions the exploited process gets on the rest of the system.
- M1050 Exploit Protection (for T1190) : Web Application Firewalls may be used to limit exposure of applications to prevent exploit traffic from reaching the application.
- M1035 Limit Access to Resource Over Network (for T1190) : Ensure that all publicly exposed services are actually intended to be so, and restrict access to any that should only be available internally.
- M1051 Update Software (for T1190) : Update software regularly by employing patch management for externally exposed applications.
Detection Generic guidance
- Initial Access: Alert on unusual requests to the affected service (odd paths, oversized payloads, exploit strings) in WAF, reverse-proxy and application logs.
Response checklist Generic guidance
- Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
- Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
- Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
- Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.