CVE-2018-13383
Fortinet FortiOS and FortiProxy Out-of-bounds Write
- Medium 4.3
- Exploited: added to CISA KEV 10 Jan 2022
- Used in ransomware campaigns
Description
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.
Key facts
- Published
- 29 May 2019
- Last changed
- 21 Oct 2025
- Assigned by
- fortinet
- KEV added
- 10 Jan 2022
- KEV fix due
- 10 Jul 2022
- Used in ransomware
- Yes, according to CISA
- EPSS
- 30.67% likely to be exploited in the next 30 days, higher than 98.274% of CVEs (scores for 15 Nov 2026)
- SSVC (CISA)
- Exploitation: active; Automatable: no; Technical impact: partial
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 4.3CVSS 3.1, Mediumfrom the CNA (fortinet)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
What to do
- Apply updates per vendor instructions.CISA KEV required action
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Affected products
| Vendor | Product | Versions |
|---|---|---|
| Fortinet | Fortinet FortiOS and FortiProxy |
|
Timeline
- 29 May 2019 Published
- 10 Jan 2022 CVE-2018-13383 added to CISA KEV
- 10 Jan 2022 Added to the CISA KEV catalogue