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Vulnerabilities

MediumKEVRansomware

CVE-2018-13383 — Fortinet FortiOS and FortiProxy Out-of-bounds Write

CVE-2018-13383 · Fortinet FortiOS and FortiProxy · CVSS 6.5 · KEV

In brief

Severity · CVSS
Medium6.5CVSS 3.1, Medium
EPSS
34%
CISA KEV
Known exploited, listed since 10 Jan 2022
CERT-FR
No advisory or alert referenced in the catalog
Vendor
Fortinet
Published · Modified
·
Last verified

Summary

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.

Weakness: CWE-787

Title, description and the vendor's statements are quoted from the CVE record; a vendor's advisory is summarised in Patcharo's words, with a link.

Affected and fixed versions

Per product and release branch, as the vendor's CVE record and official advisory state them. A fixed release is shown only when a document names it: the vendor's, or CERT-FR's for Check Point, with its source.

No precise fixed release is published in the sources Patcharo follows.

Fortinet FortiOS and FortiProxy

Source: CVE-2018-13383

  1. —
    Affected versionsFortiOS 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
    First fixed releaseNot published in the sources followed

No precise fixed release is published for this product in the sources Patcharo follows.

Remediation

Vendor guidance

CISA KEV required action

Apply updates per vendor instructions.

CISA due date:

SourceCISA KEV

Vendor advisory

The vendor has published an advisory for this CVE: check it for fixed releases and mitigations.

Sourcehttps://fortiguard.com/advisory/FG-IR-18-388

Sourcehttps://fortiguard.com/advisory/FG-IR-20-229

Last verified 1 Oct 2026 at 09:30 UTC

Known exploitation

Added to CISA KEV on 10 Jan 2022

Federal remediation due date: 10 Jul 2022

Known use in ransomware campaigns

The CISA required action is shown under Remediation.

34% probability of exploitation in the next 30 days (percentile 98%).

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

CERT-FR

No CERT-FR advisory or alert of the last two years references this CVE, for the vendors Patcharo covers.

Timeline

  1. Published by the source
  2. Added to CISA KEV
  3. CISA remediation due date
  4. Source record last modified
  5. EPSS score computed
  6. Last verified by Patcharo

Official sources

Vendor advisory

References

Fortinet · CISA Known Exploited Vulnerabilities · NVD · FIRST EPSS

How Patcharo reads this

Affected and fixed releases come from the vendor's structured statements and are matched against exact versions; CVSS from NVD, exploitation from CISA KEV and the vendor's own advisory, probability from FIRST EPSS. Missing data stays Unknown and never becomes Not affected.

Read the methodologyRead the guide: FortiOS version numbering: branches, patch releases and the Feature and Mature labels