CVE-2021-43071Network attack vector

Authenticated code execution via API heap overflow

Published Dec 9, 2021 · Updated Oct 25, 2024

Heap-based buffer overflow in FortiWeb 6.2.0 through 6.2.6, 6.3.0 through 6.3.16, 6.4.0, and 6.4.1 allows remote authenticated users to execute code. The LogAccess and LogReport API v1.0 controllers mishandle crafted HTTP request data and write beyond a heap buffer. Authentication is required; successful exploitation permits unauthorized commands and can compromise or interrupt the appliance.

CVSS severity8.8
High
EPSS probability1.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Heap-based buffer overflow in FortiWeb 6.2.0 through 6.2.6, 6.3.0 through 6.3.16, 6.4.0, and 6.4.1 allows remote authenticated users to execute code. The LogAccess and LogReport API v1.0 controllers mishandle crafted HTTP request data and write beyond a heap buffer. Authentication is required; successful exploitation permits unauthorized commands and can compromise or interrupt the appliance.

The record

CVE
CVE-2021-43071
Published
Dec 9, 2021
Updated
Oct 25, 2024
Vendor
Fortinet
Product
FortiWeb
Classifications
CWE-787, CWE-122, CAPEC-92, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 9, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

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, 6.3.16, 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, 6.2.6, 6.2.5, 6.2.4, 6.2.3, 6.2.2, 6.2.1, 6.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Fortinet · FortiWebversion=FortiWeb 6.4.1, 6.4.0, 6.3.16, 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, 6.2.6, 6.2.5, 6.2.4, 6.2.3, 6.2.2, 6.2.1, 6.2.0

Published CVSS scores

8.8FortinetCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.3FortinetCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:C
6.5NVDAV:N/AC:L/Au:S/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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
CWE-122Heap-based Buffer Overflow
CAPEC-92Forced Integer Overflow
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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo