CVE-2021-28800Network attack vector

Unauthenticated remote command execution

Published Jun 24, 2021 · Updated Sep 16, 2024

Command injection in QNAP QTS before 4.3.3.1624 or 4.3.6.1663 allows remote attackers to execute arbitrary commands over the network. QNAP has not disclosed the affected component, input vector, or unsafe command-construction operation. Network access without authentication or user interaction is sufficient, but exploitation requires high-complexity conditions and yields command execution in the compromised application.

CVSS severity8.1
High
EPSS probability1.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in QNAP QTS before 4.3.3.1624 or 4.3.6.1663 allows remote attackers to execute arbitrary commands over the network. QNAP has not disclosed the affected component, input vector, or unsafe command-construction operation. Network access without authentication or user interaction is sufficient, but exploitation requires high-complexity conditions and yields command execution in the compromised application.

The record

CVE
CVE-2021-28800
Published
Jun 24, 2021
Updated
Sep 16, 2024
Vendor
Linn Products Limited
Product
QTS
Classifications
CWE-78, T1059
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 24, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <4.3.3.1624 Build 20210416
  2. Affected versionversion=unspecified <4.3.6.1663 Build 20210504

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Linn Products Limited · QTSversion=unspecified <4.3.3.1624 Build 20210416; version=unspecified <4.3.6.1663 Build 20210504

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.1QNAP Systems, Inc.CVSS:3.1/AV:N/AC:H/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.

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-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059Command and Scripting Interpreter

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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