Threats / Fortinet / CVE-2018-13383
CVE-2018-13383
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Fortinet FortiOS and FortiProxy vulnerability
A heap buffer overflow in FortiOS and FortiProxy SSL VPN web service allows remote attackers to cause denial of service by terminating the service for authenticated users.
Verdict
Today item, not a backlog item.
This vulnerability enables unauthenticated remote denial of service against SSL VPN infrastructure. The heap overflow permits memory corruption that crashes the VPN service, disrupting legitimate user sessions and potentially enabling lateral movement or persistence in compromised environments.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
2 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-01-10), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.33647 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Fortinet, FortiOS and FortiProxy. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-787 Out-of-bounds Write — weakness family: Memory safety.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious SSL VPN request that triggers a heap buffer overflow in the web service.
Business
The SSL VPN service crashes, disconnecting all authenticated users and blocking remote access to corporate resources.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I repeatedly trigger the overflow to maintain persistent denial of service against the VPN gateway.
Business
Sustained unavailability of remote access infrastructure prevents employees from working and disrupts business continuity.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05