CVE-2018-13379: Fortinet FortiOS SSL VPN Path Traversal Vulnerability

Vulnerability summary

CVE-2018-13379 is a critical (CVSS 9.8) Path Traversal vulnerability in Fortinet FortiOS. It is known to be exploited: CISA lists it, first on 03-11-2021. It has been used in ransomware campaigns. EPSS estimates a 100.00% chance of exploitation in the next 30 days, higher than 99.9% of scored vulnerabilities. 3 public exploits are recorded.

Timeline

1. 04-06-2019
   PublishedVulnerability first disclosed.
2. 03-11-2021
   Added to CISA KEVFortinet FortiOS SSL VPN Path Traversal Vulnerability
3. 03-05-2022
   CISA remediation dueApply updates per vendor instructions.
4. 21-10-2025
   Last modifiedVulnerability information updated.

Description

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.

• CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.