LiveActive security incident?Get immediate response
CVE Record

CVE-2021-36187: A uncontrolled resource consumption in Fortinet FortiWeb version 6.4.0, version 6.3.15 and below, 6.2.5 and...

A uncontrolled resource consumption in Fortinet FortiWeb version 6.4.0, version 6.3.15 and below, 6.2.5 and below allows attacker to cause a denial of service for webserver daemon via crafted HTTP requests

MediumCVSS 5.3Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-36187 is a denial-of-service issue in Fortinet FortiWeb. An unauthenticated attacker could send crafted HTTP requests that consume resources and disrupt the webserver daemon. The sources indicate availability impact only, not data theft or system takeover.

Executive priority

Treat as a service-availability risk. It is not rated critical, but exposed FortiWeb appliances protecting revenue or customer-facing applications should be remediated promptly to reduce outage risk.

Technical view

FortiWeb versions 6.4.0, 6.3.15 and below, and 6.2.5 and below are reported affected, with many older versions listed. CVSS 3.1 is 5.3: network reachable, low complexity, no privileges, no user interaction, unchanged scope, and low availability impact.

Likely exposure

Exposure is most relevant where affected FortiWeb appliances process HTTP traffic from untrusted networks. Internet-facing deployments carry higher business risk because the attack vector is network-based and unauthenticated.

Exploitation context

The bundle does not show CISA KEV listing or confirmed active exploitation. The CVSS vector lists exploit code maturity as proof-of-concept, but the provided sources do not include exploit details.

Researcher notes

The source bundle identifies uncontrolled resource consumption via crafted HTTP requests, but provides no CWE, no request details, and no named workaround. Avoid assuming compromise impact beyond denial of service unless Fortinet advisory evidence adds it.

Mitigation direction

  • Check Fortinet advisory FG-IR-21-039 for official fixed versions and guidance.
  • Upgrade affected FortiWeb systems to a vendor-supported, non-affected release.
  • Prioritize Internet-facing FortiWeb appliances and critical application paths.
  • Monitor FortiWeb webserver daemon health and availability during remediation.

Validation and detection

  • Inventory FortiWeb appliances and record exact firmware versions.
  • Compare versions against the affected ranges in the CVE source bundle.
  • Identify appliances receiving HTTP traffic from untrusted networks.
  • Review monitoring for recent webserver daemon restarts or availability degradation.
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.

cve · low confidence lookup

CVE-2021-36187 mapping review

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

Open ATT&CK lookup
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/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
5.3CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:X/RC:C3.91.4Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.3Medium
CVSS 3.1 vector shape for CVE-2021-36187Attack 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/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, 6.2.0, 6.1.2, 6.1.1, 6.1.0, 6.0.7, 6.0.6, 6.0.5, 6.0.4, 6.0.3, 6.0.2, 6.0.1, 6.0.0, 5.9.1, 5.9.0, 5.8.7, 5.8.6, 5.8.5, 5.8.3, 5.8.2, 5.8.1, 5.8.0, 5.7.3, 5.7.2, 5.7.1, 5.7.0, 5.6.2, 5.6.1, 5.6.0, 5.5.7, 5.5.6, 5.5.5, 5.5.4, 5.5.3, 5.5.2, 5.5.1, 5.5.0, 5.4.1, 5.4.0, 5.3.9, 5.3.8, 5.3.7, 5.3.6, 5.3.5, 5.3.4, 5.3.3, 5.3.2, 5.3.1, 5.3.0, 5.2.4, 5.2.3, 5.2.2, 5.2.1, 5.2.0, 5.1.4, 5.1.3, 5.1.2, 5.1.1, 5.1.0, 5.0.6, 5.0.5, 5.0.4, 5.0.3, 5.0.2, 5.0.1, 5.0.0, 4.4.7, 4.4.6, 4.4.5, 4.4.4, 4.4.3, 4.4.2, 4.4.1, 4.4.0, 4.3.7, 4.3.6, 4.3.5, 4.3.4, 4.3.3, 4.3.2, 4.3.1, 4.2.4, 4.2.3, 4.2.2, 4.2.0, 4.1.2, 4.1.1, 4.1.0, 4.0.2, 3.0.0Listed
Weakness

CWE details

No CWE listed

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