CVE-2021-36186

Unauthenticated code execution via crafted HTTP requests

Published Nov 2, 2021 · Updated Oct 25, 2024

Stack-based buffer overflow in Fortinet FortiWeb 6.4.0, 6.3.15 and earlier, and 6.2.5 and earlier allows remote attackers to execute code. Fortinet identifies crafted HTTP requests as the trigger but has not disclosed the affected request-handling function or the operation that overruns its stack buffer. No authentication or user interaction is required, and successful exploitation grants unauthorized code or command execution from an adjacent network.

CVSS severity8.8
High
EPSS probability1.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in Fortinet FortiWeb 6.4.0, 6.3.15 and earlier, and 6.2.5 and earlier allows remote attackers to execute code. Fortinet identifies crafted HTTP requests as the trigger but has not disclosed the affected request-handling function or the operation that overruns its stack buffer. No authentication or user interaction is required, and successful exploitation grants unauthorized code or command execution from an adjacent network.

The record

CVE
CVE-2021-36186
Published
Nov 2, 2021
Updated
Oct 25, 2024
Vendor
Fortinet
Product
FortiWeb
Classifications
CWE-787, T1190
Attack vector
adjacent
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

What conditions does exploitation require?

Attack vectoradjacent
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

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.8FortinetCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

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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