CVE-2018-13383
KEVRansomware UseFortinet FortiOS and FortiProxy Out-of-bounds Write
Description
A heap buffer overflow in Fortinet FortiOS and FortiProxy may cause the SSL VPN web service termination for logged in users.
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 3.1 vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:LPublishedMay 29, 2019
Last modifiedJun 17, 2026
Added to KEVJan 10, 2022
Remediation dueJul 10, 2022
References
- fortiguard.com/advisory/FG-IR-18-388MitigationVendor Advisory
- fortiguard.com/advisory/FG-IR-20-229Vendor Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-13383US Government Resource
0 recent articles mention this CVE
65
Risk assessment · High
Actively exploited and used by ransomware crews. Patch immediately.
- Exploitation
- Confirmed in the wild (CISA KEV)
- Federal remediation deadline
- Overdue by 1569 days
- Ransomware
- Used in known ransomware campaigns
- CVSS
- 4.3 MEDIUM
- EPSS (30-day exploit probability)
- 33.6% · top 2% of all CVEs
- Weakness
- CWE-787
- Attack vector
- Network, remotely reachable
Recommended actions
- 1.Apply updates per vendor instructions.
- 2.Treat as emergency change: patch or isolate internet-facing instances first.
- 3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
- 4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.
- 5.Verify offline/immutable backups and segment the affected systems. This flaw is used for ransomware initial access.
Assessment is derived automatically from the live signals above; verify against your own asset inventory.