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CVE-2018-13383

Published: May 29, 2019Updated: Oct 24, 2025 Sources: CVE List NVD BDUCWE-787
4.3MEDIUM
NVD MITRE
EPSS Score
33.6%
Top 1.7%
CISA KEV
Active Exploitation
Since Jan 10, 2022
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

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.

In plain language

AI Act now

CVE-2018-13383 is a Fortinet SSL VPN web portal flaw where a logged-in attacker can send malicious web content and cause the VPN web service to crash; if you run FortiOS/FortiProxy for SSL VPN, you should fix it now.

Executive summary

CVE-2018-13383 is a heap buffer overflow (CWE-787) in Fortinet FortiOS and FortiProxy SSL VPN web portal proxying that can be triggered by a logged-in user by supplying malicious JavaScript href data, leading to service termination; it is listed in CISA KEV and was used in ransomware campaigns, so affected systems should be updated per vendor guidance.

If affected, business impact
SSL VPN web access disruptionService outages for logged-in usersRansomware campaign involvementOperational disruption

What to do now

  1. Check whether your business uses Fortinet SSL VPN web portal on “fortinet fortios and fortiproxy” (FortiOS and/or FortiProxy) and whether your deployed versions fall within the affected ranges.
  2. Confirm you have logged-in SSL VPN web portal users and whether any account could be abused (lost credentials, shared accounts, weak passwords).
  3. Upgrade FortiProxy to version 1.2.9 or later.
  4. Upgrade FortiOS to version 5.2.15 or later.
  5. If you cannot upgrade immediately, apply the vendor workaround guidance from the linked FortiGuard advisories and plan an urgent upgrade as the permanent fix.
Patch / advisory Usually a quick update

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:UC:NI:NA:L
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:LAvailability
Low
Open in CVSS calculator →

Weaknesses

CWE-787

Affected Products

Fortinet
commercial·USaka forti net
Fortinet FortiOS and FortiProxy
Security Products
fortiproxy
Security Products
fortios
Security Products
Fortinet Inc.
commercial·USaka fortinet
FortiOS
Security Products

Exploitability

CISA Known Exploited Vulnerability
Added to KEV:Jan 10, 2022
Remediation due:Jul 10, 2022
Ransomware:Known ransomware use

Required action: Apply updates per vendor instructions.

Official Patch Available
Workaround Available
Is your org exposed to CVE-2018-13383?We can run the check for you — a free external exposure review, no install. Check my exposure

Attack Graph

Products CVE Techniques Tactics

Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.

MITRE ATT&CK

2 techniques
Initial Access
Privilege Escalation
View detailed technique mapping

References

https://fortiguard.com/advisory/FG-IR-18-388
fortiguard.com
https://fortiguard.com/advisory/FG-IR-20-229
fortiguard.com
https://fortiguard.com/psirt/FG-IR-18-388
fortiguard.com
and 4 more references View all →

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