CVE-2021-3897Network attack vector

Unauthenticated command execution via internal service bypass

Published Apr 22, 2022 · Updated Aug 3, 2024

Authentication bypass in Lenovo FPC2 and SMM firmware allows remote attackers to execute commands through a network-reachable internal service. The internal service accepts command-execution requests without enforcing authentication, but Lenovo has not disclosed the affected handler or request format. Network access to the management controller is sufficient; exploitation grants control of FPC2 or SMM firmware, while SMM2 is unaffected.

CVSS severity9.8
Critical
EPSS probability1.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Lenovo FPC2 and SMM firmware allows remote attackers to execute commands through a network-reachable internal service. The internal service accepts command-execution requests without enforcing authentication, but Lenovo has not disclosed the affected handler or request format. Network access to the management controller is sufficient; exploitation grants control of FPC2 or SMM firmware, while SMM2 is unaffected.

The record

CVE
CVE-2021-3897
Published
Apr 22, 2022
Updated
Aug 3, 2024
Vendor
Lenovo
Product
Lenovo Fan Power Controller2 (FPC2) Firmware
Classifications
CWE-288, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 22, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=various

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Lenovo · Lenovo Fan Power Controller2 (FPC2) Firmwareversion=various
Lenovo · Lenovo System Management Module Firmwareversion=various

Published CVSS scores

9.8Lenovo Group Ltd.CVSS:3.1/AV:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-288Authentication Bypass Using an Alternate Path or Channel
T1210Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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