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

Medium severity, CVSS 6.5. Actively exploited: in CISA KEV since 2022-01-10. EPSS: 33.6% chance of exploitation in the next 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.

Affected products

• Fortinet FortiOS: from 5.2.0, before 5.2.15 (fixed in 5.2.15); from 5.4.0, before 5.4.13 (fixed in 5.4.13); from 5.6.0, before 5.6.11 (fixed in 5.6.11); from 6.0.0, before 6.0.5 (fixed in 6.0.5)
• Fortinet FortiProxy: before 1.2.9 (fixed in 1.2.9); version 2.0.0 only

Published 2019-05-29. Last modified 2026-06-17.