CVE-2021-22129Network attack vector

Authenticated code execution via buffer size miscalculation

Published Jul 9, 2021 · Updated Oct 25, 2024

Buffer overflow in FortiMail before 6.4.5 allows remote authenticated users with regular webmail access to execute unauthorized code via crafted HTTP requests. The webmail and administrative interfaces miscalculate buffer sizes when copying request data, allowing an oversized value to overwrite adjacent memory. Regular webmail authentication is required, and successful exploitation can compromise confidentiality, integrity, and availability of the appliance.

CVSS severity8.8
High
EPSS probability1.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in FortiMail before 6.4.5 allows remote authenticated users with regular webmail access to execute unauthorized code via crafted HTTP requests. The webmail and administrative interfaces miscalculate buffer sizes when copying request data, allowing an oversized value to overwrite adjacent memory. Regular webmail authentication is required, and successful exploitation can compromise confidentiality, integrity, and availability of the appliance.

The record

CVE
CVE-2021-22129
Published
Jul 9, 2021
Updated
Oct 25, 2024
Vendor
Fortinet
Product
FortiMail
Classifications
CWE-120, T1210
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 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

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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=FortiMail before 6.4.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Fortinet · FortiMailversion=FortiMail before 6.4.5

Published CVSS scores

6.5NVDAV:N/AC:L/Au:S/C:P/I:P/A:P
8.8NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.8Fortinet PSIRTCVSS: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.

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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-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1210Exploitation of Remote Services

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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