CVE-2021-41027

Authenticated code execution via crafted certificate loading

Published Dec 8, 2021 · Updated Oct 25, 2024

Stack-based buffer overflow in Fortinet FortiWeb 6.4.0 and 6.4.1 allows local users to execute code by loading a crafted certificate. Fortinet attributes the overflow to a type mismatch during certificate loading but has not published the affected function or exact operation that overruns the stack buffer. Exploitation requires authenticated access and user interaction to load the certificate, after which attacker-controlled code or commands run on the appliance.

CVSS severity7.3
High
EPSS probability0.16%
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 and 6.4.1 allows local users to execute code by loading a crafted certificate. Fortinet attributes the overflow to a type mismatch during certificate loading but has not published the affected function or exact operation that overruns the stack buffer. Exploitation requires authenticated access and user interaction to load the certificate, after which attacker-controlled code or commands run on the appliance.

The record

CVE
CVE-2021-41027
Published
Dec 8, 2021
Updated
Oct 25, 2024
Vendor
Fortinet
Product
FortiWeb
Classifications
CWE-787, T1204.002
Attack vector
local
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

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Fortinet · FortiWebversion=FortiWeb 6.4.1, 6.4.0

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.9FortinetCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H/E:P/RL:X/RC:C
7.3FortinetCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
4.6NIST NVDAV:L/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1204.002User Execution: Malicious File

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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