CVE-2021-34359Network attack vector

Authenticated browser code execution via undisclosed input

Published Feb 25, 2022 · Updated Sep 17, 2024

Cross-site scripting in QNAP Proxy Server before 1.4.2 allows remote authenticated users to inject code through an undisclosed web input. QNAP has not identified the affected page, parameter, or whether the application stores or reflects the unsanitized value before a browser interprets it. Exploitation requires privileged access and victim interaction; code runs in the victim's browser with confidentiality and integrity impact but no reported service interruption.

CVSS severity6.9
Medium
EPSS probability0.62%
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 Proxy Server before 1.4.2 allows remote authenticated users to inject code through an undisclosed web input. QNAP has not identified the affected page, parameter, or whether the application stores or reflects the unsanitized value before a browser interprets it. Exploitation requires privileged access and victim interaction; code runs in the victim's browser with confidentiality and integrity impact but no reported service interruption.

The record

CVE
CVE-2021-34359
Published
Feb 25, 2022
Updated
Sep 17, 2024
Vendor
Linn Products Limited
Product
Proxy Server
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Feb 25, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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=unspecified <1.4.2 ( 2021/12/30 )

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Linn Products Limited · Proxy Serverversion=unspecified <1.4.2 ( 2021/12/30 )

Published CVSS scores

6.9QNAP Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:L/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript

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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