Background exploitation KEV catalog Ransomware No authentication

CVE-2018-13379

Fortinet FortiOS SSL VPN Path Traversal Vulnerability

CheckOps priority index

9.6/10 Patch within 24 h

Severity9.1

Probability10.0

Exploitation5/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 100.00% higher than 99.99% of CVEs

CVSS 3.1 9.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:

Exploited for 1,826 days 03 Nov 2021

CISA due date 03 May 2022 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 5 / 5

KEV catalog (CISA)03 Nov 2021
Exploited in EUVD (ENISA)03 Nov 2021
Used by ransomwareyes
EPSS above 10 %100.00%
No account, over the networkyes

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply updates per vendor instructions.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Description ENISA EUVD

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.

Affected products

Fortinet FortiOS, FortiProxyFortiOS

Affected versions

FortiOS 6.0.0 to 6.0.4, 5.6.3 to 5.6.7 and 5.4.6 to 5.4.12, 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

Weaknesses (CWE)

CWE-22

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

04 Jun 2019
Published
03 Nov 2021
Exploitation reported (ENISA)
03 Nov 2021
Added to the KEV catalog
03 May 2022
CISA remediation due date
26 Sept 2026
EPSS peak: 100.00%

References

Other exploited vulnerabilities from the same vendor

CVE-2025-61624Fortinet Multiple Products Path Traversal Vulnerability
3.4 · Rising fast
CVE-2026-104286Fortinet FortiMail Path Traversal Vulnerability
5.9 · Actively exploited
CVE-2025-25249Fortinet Multiple Products Heap-based Buffer Overflow Vulnerability
4.9 · Actively exploited
CVE-2025-68686Fortinet FortiOS Exposure of Sensitive Information to an Unauthorized Actor Vulnerability
5.4 · Actively exploited
CVE-2026-39808Fortinet FortiSandbox OS Command Injection Vulnerability
8.8 · Actively exploited
CVE-2026-25089Fortinet FortiSandbox OS Command Injection Vulnerability
8.3 · Actively exploited