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Vulnerabilities

Vulnerability · CVE-2018-13383

Fortinet FortiOS and FortiProxy Out-of-bounds Write

Published May 29, 2019 · catalog updated Jun 16, 2026 · Fortinet FortiOS and FortiProxy

Patch now

CVE-2018-13383 is in the CISA known-exploited catalog, due Jul 10, 2022. Confirm Fortinet FortiOS and FortiProxy against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Severity
Medium6.5
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
33.65%
Remediation
Remediation guidance
Affected products
cpe fortinet/fortios · cpe fortinet/fortiproxy · vendor Fortinet FortiOS and FortiProxy

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe fortinet/fortiosversion unspecified
  • cpe fortinet/fortiproxy2.0.0
  • vendor Fortinet FortiOS and FortiProxyversion unspecified

How to fix CVE-2018-13383

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2018-13383 is in the CISA known-exploited catalog, due Jul 10, 2022. Confirm Fortinet FortiOS and FortiProxy against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Compare what you have installed with 2.0.0. Apply updates per vendor instructions.

What should an analyst verify?

CWE-787: Out-of-bounds Write. EPSS 33.65%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Fortinet security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. May 29, 2019 · Catalog

    Detected

    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.

  2. Jan 10, 2022 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Jul 10, 2022 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    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.

Sources

  • CISA KEVConfirmed exploitationCVE-2018-13383

    A heap buffer overflow in Fortinet FortiOS and FortiProxy may cause the SSL VPN web service termination for logged in users.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2018-13383

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2018-13383

    30-day exploitation probability 33.6%

    first.org
  • NIST NVDVulnerability recordCVE-2018-13383

    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 p

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2018-13383

    A heap buffer overflow in Fortinet FortiOS and FortiProxy may cause the SSL VPN web service termination for logged in users.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.