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CVE Record

CVE-2021-36186: A stack-based buffer overflow in Fortinet FortiWeb version 6.4.0, version 6.3.15 and below, 6.2.5 and below...

A stack-based buffer overflow in Fortinet FortiWeb version 6.4.0, version 6.3.15 and below, 6.2.5 and below allows attacker to execute unauthorized code or commands via crafted HTTP requests

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2021-36186 is a high-severity Fortinet FortiWeb flaw that can let an attacker run unauthorized code or commands by sending crafted HTTP requests. For businesses using affected FortiWeb versions, this threatens confidentiality, integrity, and availability of the appliance and traffic it protects.

Executive priority

Treat this as a high-priority perimeter security issue where affected FortiWeb systems exist. Remediation should be scheduled promptly because successful exploitation could compromise the appliance’s control over protected web traffic.

Technical view

The source describes a stack-based buffer overflow in Fortinet FortiWeb 6.4.0, 6.3.15 and below, and 6.2.5 and below. CVSS 3.1 score is 8.8 with no privileges or user interaction required, adjacent attack vector, low complexity, and high CIA impact.

Likely exposure

Exposure is limited to Fortinet FortiWeb deployments running the listed affected versions. Risk depends on whether attackers can reach the relevant HTTP request handling surface from the applicable network path.

Exploitation context

The bundle does not show CISA KEV listing or active exploitation evidence. The CVSS vector includes exploit maturity E:P, indicating proof-of-concept status in the scoring data, but no weaponization details are provided.

Researcher notes

Evidence is sufficient for affected-version triage and severity, but the bundle lacks detailed root-cause, patch-version, and workaround text. Do not infer affected products beyond Fortinet FortiWeb or claim active exploitation without additional sources.

Mitigation direction

  • Identify all FortiWeb appliances and record exact firmware versions.
  • Review Fortinet advisory FG-IR-21-119 for fixed versions or official workarounds.
  • Prioritize vendor-supported remediation for affected FortiWeb versions.
  • Limit reachable attack surface while awaiting or applying Fortinet guidance.

Validation and detection

  • Compare deployed FortiWeb versions against the affected version list.
  • Confirm remediation status using Fortinet advisory FG-IR-21-119.
  • Check asset exposure from relevant network zones without attempting exploitation.
  • Review FortiWeb logs for unusual HTTP request handling errors or crashes.
Prepared
Confidence
high
Sources
3

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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

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CVE-2021-36186 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:C

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
2Source 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
8.8CVSS 3.1HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:C2.85.9Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

8.8High
CVSS 3.1 vector shape for CVE-2021-36186Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:C

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 FortiWebFortiWeb 6.4.0, 6.3.15, 6.3.14, 6.3.13, 6.3.12, 6.3.11, 6.3.10, 6.3.9, 6.3.8, 6.3.7, 6.3.6, 6.3.5, 6.3.4, 6.3.3, 6.3.2, 6.3.1, 6.3.0, 6.2.5, 6.2.4, 6.2.3, 6.2.2, 6.2.1, 6.2.0Listed
Weakness

CWE details

No CWE listed

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