CVE-2021-41017Network attack vector

Authenticated code execution via web API heap overflows

Published Dec 8, 2021 · Updated Oct 25, 2024

Heap-based buffer overflows in Fortinet FortiWeb 6.3.0 through 6.3.15 and 6.4.0 through 6.4.1 allow remote authenticated users to execute code. Crafted HTTP requests reach affected web API controllers, where request processing performs an undisclosed out-of-bounds write into heap memory. A valid authenticated session is required; successful exploitation can execute arbitrary code or commands and can fully compromise the appliance.

CVSS severity8.8
High
EPSS probability1.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflows in Fortinet FortiWeb 6.3.0 through 6.3.15 and 6.4.0 through 6.4.1 allow remote authenticated users to execute code. Crafted HTTP requests reach affected web API controllers, where request processing performs an undisclosed out-of-bounds write into heap memory. A valid authenticated session is required; successful exploitation can execute arbitrary code or commands and can fully compromise the appliance.

The record

CVE
CVE-2021-41017
Published
Dec 8, 2021
Updated
Oct 25, 2024
Vendor
Fortinet
Product
FortiWeb
Classifications
CWE-787, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 8, 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 6.4.1, 6.4.0, 6.3.0 through 6.3.15

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Fortinet · FortiWebversion=FortiWeb 6.4.1, 6.4.0, 6.3.0 through 6.3.15

Published CVSS scores

6.5NIST National Vulnerability DatabaseAV:N/AC:L/Au:S/C:P/I:P/A:P
8.8Fortinet, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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
Privilegesauthenticated
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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