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CVE Record

CVE-2018-13381: A buffer overflow vulnerability in Fortinet FortiOS 6.0.0 through 6.0.4, 5.6.0 through 5.6.7, 5.4 and earli...

A buffer overflow vulnerability in Fortinet FortiOS 6.0.0 through 6.0.4, 5.6.0 through 5.6.7, 5.4 and earlier versions and FortiProxy 2.0.0, 1.2.8 and earlier versions under SSL VPN web portal allows a non-authenticated attacker to perform a Denial-of-service attack via special craft message payloads.

MediumCVSS 5.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This flaw affects Fortinet SSL VPN web portals on older FortiOS and FortiProxy versions. An unauthenticated remote attacker could crash or disrupt the service, causing availability impact. The provided sources do not indicate data theft, privilege escalation, or active exploitation.

Executive priority

Schedule remediation in the normal vulnerability cycle, faster for internet-facing VPN portals. Business risk is service disruption rather than confirmed compromise, but VPN availability is operationally important.

Technical view

CVE-2018-13381 is a buffer overflow in the SSL VPN web portal affecting FortiOS 6.0.0-6.0.4, 5.6.0-5.6.7, 5.4 and earlier, and FortiProxy 2.0.0, 1.2.8 and earlier. CVSS 3.1 is 5.3: network reachable, low complexity, no privileges or user interaction, availability impact only.

Likely exposure

Exposure is most likely where Fortinet SSL VPN web portals are internet-facing and run the listed FortiOS or FortiProxy versions. Internal-only portals reduce reach but still matter if reachable by untrusted networks.

Exploitation context

The bundle says attacks require specially crafted message payloads and no authentication. KEV is false, and no cited source in the bundle confirms active exploitation. Treat exploit status as unconfirmed from the supplied evidence.

Researcher notes

The source bundle identifies a buffer overflow but provides no CWE entry and no exploit details. CVSS indicates no confidentiality or integrity impact. Do not infer remote code execution or credential exposure from the provided evidence.

Mitigation direction

  • Check Fortinet advisories FG-IR-18-387 and FG-IR-20-232 for fixed releases and guidance.
  • Inventory FortiOS and FortiProxy appliances running affected versions.
  • Prioritize upgrading or remediating internet-facing SSL VPN portals first.
  • Restrict SSL VPN portal access to trusted networks where operationally feasible.
  • Monitor SSL VPN service stability until remediation is confirmed.

Validation and detection

  • Identify all Fortinet SSL VPN web portals and their software versions.
  • Compare versions against the affected FortiOS and FortiProxy ranges.
  • Confirm whether each SSL VPN web portal is exposed to the internet.
  • Review monitoring for unexplained SSL VPN crashes or availability degradation.
  • Document remediation status for each affected appliance.
Prepared
Confidence
high
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2018-13381 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.3 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
5.3CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L3.91.4Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.3Medium
CVSS 3.1 vector shape for CVE-2018-13381Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
FortinetFortinet FortiOS and FortiProxyFortiOS 6.0.0 through 6.0.4, 5.6.0 through 5.6.7, 5.4 and earlier and FortiProxy 2.0.0, 1.2.8 and earlier.Listed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.