CVE-2021-34343Network attack vector

Authenticated arbitrary code execution via stack overflow

Published Sep 10, 2021 · Updated Sep 16, 2024

A stack buffer overflow in QNAP QTS, QuTS hero, and QuTScloud before their fixed releases allows remote authenticated users to execute arbitrary code over network services. The vulnerable component and exact input path are not disclosed in QNAP's advisory or CVE record, which only identifies a stack-based overwrite. Exploitation requires the high-privilege access reflected in the published CVSS assessment; successful exploitation can compromise confidentiality, integrity, and availability.

CVSS severity6.0
Medium
EPSS probability1.95%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A stack buffer overflow in QNAP QTS, QuTS hero, and QuTScloud before their fixed releases allows remote authenticated users to execute arbitrary code over network services. The vulnerable component and exact input path are not disclosed in QNAP's advisory or CVE record, which only identifies a stack-based overwrite. Exploitation requires the high-privilege access reflected in the published CVSS assessment; successful exploitation can compromise confidentiality, integrity, and availability.

The record

CVE
CVE-2021-34343
Published
Sep 10, 2021
Updated
Sep 16, 2024
Vendor
Linn Products Limited
Product
QuTS hero
Classifications
CWE-787, T1190
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Sep 10, 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 <h4.5.4.1771 build 20210825

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Linn Products Limited · QuTS heroversion=unspecified <h4.5.4.1771 build 20210825
Linn Products Limited · QuTScloudversion=unspecified <c4.5.6.1755
Linn Products Limited · QTSversion=unspecified <4.5.4.1715 build 20210630; version=unspecified <5.0.0.1716 build 20210701

Published CVSS scores

6.0NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1190Exploitation of Public-Facing Application

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

See the directory against your own environment.

Your stack

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