Fortinet · FortiOS and FortiProxy
CVE-2018-13383
Fortinet FortiOS and FortiProxy Out-of-bounds Write
What it is
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.
CISA: A heap buffer overflow in Fortinet FortiOS and FortiProxy may cause the SSL VPN web service termination for logged in users.
What to do
Apply updates per vendor instructions.
Deadline for US federal agencies: July 10, 2022
More exploited flaws from Fortinet
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| Mar 18, 2025 | Authentication Bypass | FortiOS and FortiProxy | High 8.1 | 7.2% |
| Jan 14, 2025 | Authentication Bypass | FortiOS and FortiProxy | Critical 9.6 | 94% |
| Jan 10, 2022 | Improper Authorization | FortiOS and FortiProxy | Critical 9.1 | 82% |
| Oct 16, 2026 | Path Traversal | Multiple Products | Medium 5.4 | 1.3% |
| Oct 1, 2026 | Path Traversal | FortiMail | Critical 9.8 | 4.6% |
| Sep 9, 2026 | Heap-based Buffer Overflow | Multiple Products | High 7.4 | 3.7% |
| Jul 27, 2026 | Exposure of Sensitive Information to an Unauthorized Actor | FortiOS | Medium 5.3 | 29% |
| Jul 16, 2026 | OS Command Injection | FortiSandbox | Critical 9.1 | 76% |
Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.