Medium 4.3Known exploited (CISA KEV)Published May 29, 2019

CVE-2018-13383A 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 ca…

Updated under an hour ago (2026-10-19 04:00 UTC)

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It affects Fortinet FortiOS and FortiProxy and 2 other products. Add what you run to find out whether that includes you.

CISA lists it as known exploited since Jan 10, 2022; federal agencies had to remediate by Jul 10, 2022, and it is known to be used in ransomware. Treat that date as your deadline.

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Every CVE for Fortinet FortiOS and FortiProxy

Exploited in the last 30 days

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.

CVSS: 4.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Weakness (CWE): CWE-787
Known exploited: Added to CISA KEV Jan 10, 2022; federal remediation due Jul 10, 2022; known ransomware useApply updates per vendor instructions.
EPSS (exploitation in the next 30 days): 33.65% (percentile 98)
Assigned by: fortinet
NVD analysis: Analyzed
Record last updated: Oct 21, 2025
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Fortinet Fortinet FortiOS and FortiProxy fortinet:fortios_and_fortiproxy (from the name)	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	CNA record
fortinet fortiproxy fortinet:fortiproxy	before 1.2.9; 2.0.0	NVD
fortinet fortios fortinet:fortios	from 5.2.0 before 5.2.15; from 5.4.0 before 5.4.13; from 5.6.0 before 5.6.11; from 6.0.0 before 6.0.5	NVD

References

https://fortiguard.com/advisory/FG-IR-18-388x-refsource-confirm, mitigation, vendor-advisory
https://fortiguard.com/advisory/FG-IR-20-229x-refsource-confirm, vendor-advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-13383us-government-resource

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.