CVE-2021-20991Public exploitNetwork attack vector

Root command execution via unsanitized backup version

Published Apr 19, 2021 · Updated Sep 16, 2024

OS command injection in Fibaro Home Center 2 and Lite firmware 4.540 and earlier allows remote authenticated users to execute commands as root. The backup restore handler passes its unsanitized version parameter into an exec() shell command. An authenticated management-interface session is required, and successful exploitation grants full control of the appliance.

CVSS severity8.8
High
EPSS probability5.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in Fibaro Home Center 2 and Lite firmware 4.540 and earlier allows remote authenticated users to execute commands as root. The backup restore handler passes its unsanitized version parameter into an exec() shell command. An authenticated management-interface session is required, and successful exploitation grants full control of the appliance.

The record

CVE
CVE-2021-20991
Published
Apr 19, 2021
Updated
Sep 16, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-77, CWE-78, T1059.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8CERT VDECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.0NIST NVDAV:N/AC:L/Au:S/C:C/I:C/A:C
8.8NIST NVDCVSS: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.

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059.004Unix Shell

Public exploit references

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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