CVE-2021-36187Network attack vector

Webserver daemon crash via crafted HTTP requests

Published Nov 2, 2021 · Updated Oct 25, 2024

Uncontrolled resource consumption in Fortinet FortiWeb 6.2.5 and earlier, 6.3.15 and earlier, and 6.4.0 allows remote attackers to crash its webserver daemon. Fortinet has not disclosed which HTTP request field or webserver routine consumes resources without an effective limit. No authentication or user interaction is required; a crafted HTTP request can interrupt the appliance web service without affecting confidentiality or integrity.

CVSS severity5.3
Medium
EPSS probability1.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in Fortinet FortiWeb 6.2.5 and earlier, 6.3.15 and earlier, and 6.4.0 allows remote attackers to crash its webserver daemon. Fortinet has not disclosed which HTTP request field or webserver routine consumes resources without an effective limit. No authentication or user interaction is required; a crafted HTTP request can interrupt the appliance web service without affecting confidentiality or integrity.

The record

CVE
CVE-2021-36187
Published
Nov 2, 2021
Updated
Oct 25, 2024
Vendor
Fortinet
Product
FortiWeb
Classifications
CWE-400, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 2, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 25, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=FortiWeb 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, 3.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Fortinet · FortiWebversion=FortiWeb 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, 3.0.0

Published CVSS scores

5.3Fortinet, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0Fortinet, Inc.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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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