CVE-2021-3849Known exploitationNetwork attack vector

Unauthenticated command execution via web authentication bypass

Published Apr 22, 2022 · Updated Aug 3, 2024

Authentication bypass in Lenovo Fan Power Controller2 (FPC2) and System Management Module firmware allows remote attackers to execute commands. The web interface accepts command requests without verifying authentication, exposing SMM and FPC2 control functions. An attacker needs network access to the management interface but no account; successful requests can alter enclosure operation or interrupt service.

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

What happened

Authentication bypass in Lenovo Fan Power Controller2 (FPC2) and System Management Module firmware allows remote attackers to execute commands. The web interface accepts command requests without verifying authentication, exposing SMM and FPC2 control functions. An attacker needs network access to the management interface but no account; successful requests can alter enclosure operation or interrupt service.

The record

CVE
CVE-2021-3849
Published
Apr 22, 2022
Updated
Aug 3, 2024
Vendor
Lenovo
Product
Lenovo Fan Power Controller2 (FPC2) Firmware
Classifications
CWE-288, T1190
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

7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8Lenovo Group Ltd.CVSS:3.1/AV:N/AC:L/PR:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-288Authentication Bypass Using an Alternate Path or Channel
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Reported exploitation

Technologies

Your stack

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Your stack

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