Background exploitation KEV catalog Ransomware

CVE-2018-13383

Fortinet FortiOS and FortiProxy Out-of-bounds Write

A heap buffer overflow in Fortinet FortiOS 6.0.0 through 6.0.4, 5.6.0 through 5.6.10, 5.4.0 through 5.4.12, 5.2.14 and earlier and FortiProxy 2.0.0, 1.2.8 and earlier in the SSL VPN web portal may cause the SSL VPN web service termination…

CheckOps priority index

5.1/10 Patch within 7 days

Severity4.3

Probability3.2

Exploitation4/5

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

EPSS · today 32.5% −1.2 pts in 7 days

CVSS 3.1 4.3 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:

Exploited for 1,758 days 10 Jan 2022

CISA due date 10 Jul 2022 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 4 / 5

KEV catalog (CISA)10 Jan 2022
Exploited in EUVD (ENISA)10 Jan 2022
Used by ransomwareyes
EPSS above 10 %32.5%
No account, over the networkno

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

Affected products

Fortinet FortiOS and FortiProxyFortiOS and FortiProxy

Affected versions

FortiOS 6.0.0 through 6.0.4, 5.6.0 through 5.6.10, 5.4.0 through 5.4.12, 5.2.14 and earlier, FortiProxy 2.0.0, 1.2.8 and earlier

Weaknesses (CWE)

CWE-787

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

29 May 2019
Published
10 Jan 2022
Exploitation reported (ENISA)
10 Jan 2022
Added to the KEV catalog
10 Jul 2022
CISA remediation due date
26 Sept 2026
EPSS peak: 33.6%

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