CVE-2021-44053Network attack vector

Browser script execution via undisclosed input handling

Published May 5, 2022 · Updated Sep 16, 2024

Cross-site scripting in QNAP QTS, QuTS hero, and QuTScloud allows remote attackers to inject code through the web interface. QNAP has not disclosed the affected endpoint, parameter, or faulty input-handling operation. Exploitation requires user interaction, while published assessments disagree on attacker authentication; resulting code runs in the victim's browser context.

CVSS severity6.1
Medium
EPSS probability0.74%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in QNAP QTS, QuTS hero, and QuTScloud allows remote attackers to inject code through the web interface. QNAP has not disclosed the affected endpoint, parameter, or faulty input-handling operation. Exploitation requires user interaction, while published assessments disagree on attacker authentication; resulting code runs in the victim's browser context.

The record

CVE
CVE-2021-44053
Published
May 5, 2022
Updated
Sep 16, 2024
Vendor
Linn Products Limited
Product
QuTS hero
Classifications
CWE-79, T1203
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. May 5, 2022CVE 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 <h4.5.4.1971 build 20220310
  2. Affected versionversion=unspecified <h5.0.0.1986 build 20220324

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

Linn Products Limited · QuTS heroversion=unspecified <h4.5.4.1971 build 20220310; version=unspecified <h5.0.0.1986 build 20220324
Linn Products Limited · QuTScloudversion=unspecified <c5.0.1.1949
Linn Products Limited · QTSversion=unspecified <4.5.4.1991 build 20220329; version=unspecified <5.0.0.1986 build 20220324

Published CVSS scores

5.7QNAP Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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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