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CVE-2018-13383

6.5, medium Known exploited Used in ransomware

Fortinet FortiOS and FortiProxy Out-of-bounds Write

NVD (opens in a new tab) CVE.org (opens in a new tab) CISA KEV catalogue (opens in a new tab)
CVSS
6.5, medium medium CVSS v3.1
EPSS, next 30 days
34% higher than 98.3% of scored CVEs
Exploitation
Confirmed in the wild
Published
29 May 20197 years ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 10 Jan 2022 and links it to ransomware activity. US federal agencies had to remediate by 10 Jul 2022, a deadline that has passed.

Required action. Apply updates per vendor instructions.

Description

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 for logged in users due to a failure to properly handle javascript href data when proxying webpages.

Details

Vendor
Fortinet
Product
Fortinet FortiOS and FortiProxy
Weakness
CWE-787 (opens in a new tab)
Status
Analyzed
Updated
17 Jun 2026
Assigner
psirt@fortinet.com

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

References 3

Advisories 2

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Fortinet CVEs

Every Fortinet CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-104286 Fortinet FortiMail Path Traversal Vulnerability KEV EPSS 2% 9.8, critical
  • CVE-2026-25089 Fortinet FortiSandbox OS Command Injection Vulnerability KEV EPSS 76% 9.8, critical
  • CVE-2026-39808 Fortinet FortiSandbox OS Command Injection Vulnerability KEV EPSS 47% 9.8, critical
  • CVE-2026-35616 Fortinet FortiClient EMS Improper Access Control Vulnerability KEV EPSS 9% 9.8, critical
  • CVE-2025-68686 Fortinet FortiOS Exposure of Sensitive Information to an Unauthorized Actor Vulnerability KEV EPSS 29% 5.9, medium
  • CVE-2026-21643 Fortinet FortiClient EMS SQL Injection Vulnerability KEV EPSS 94% 9.8, critical
  • CVE-2026-24858 Fortinet Multiple Products Authentication Bypass Using an Alternate Path or Channel Vulnerability KEV EPSS 86% 9.8, critical
  • CVE-2025-25249 Fortinet Multiple Products Heap-based Buffer Overflow Vulnerability KEV EPSS 4% 9.8, critical

Beyond this page

Is CVE-2018-13383 in your network?

This page tells you how dangerous CVE-2018-13383 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2018-13383 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2018-13383 comes with the devices to patch.

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  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

    Learn more about EXYS7950 KONDRA
Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 16 Oct 2026, not the live upstream state.