CVE-2021-38687Network attack vector

Arbitrary code execution via stack buffer overflow

Published Dec 29, 2021 · Updated Sep 16, 2024

Stack buffer overflow in QNAP Surveillance Station on affected QTS releases allows remote attackers to execute arbitrary code. QNAP has not disclosed the affected component, input vector, or unsafe copy operation that overruns the stack buffer. Successful exploitation runs attacker-controlled code, while the execution context and required feature state remain undisclosed.

CVSS severity8.1
High
EPSS probability1.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack buffer overflow in QNAP Surveillance Station on affected QTS releases allows remote attackers to execute arbitrary code. QNAP has not disclosed the affected component, input vector, or unsafe copy operation that overruns the stack buffer. Successful exploitation runs attacker-controlled code, while the execution context and required feature state remain undisclosed.

The record

CVE
CVE-2021-38687
Published
Dec 29, 2021
Updated
Sep 16, 2024
Vendor
Linn Products Limited
Product
Surveillance Station
Classifications
CWE-120, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 29, 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 <5.1.5.3.6 ( 2021/10/26 )
  2. Affected versionversion=unspecified <5.1.5.4.6 ( 2021/10/26 )
  3. Affected versionversion=unspecified <5.2.0.3.2 ( 2021/10/26 )
  4. Affected versionversion=unspecified <5.2.0.4.2 ( 2021/10/26 )

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Linn Products Limited · Surveillance Stationversion=unspecified <5.1.5.3.6 ( 2021/10/26 ); version=unspecified <5.1.5.4.6 ( 2021/10/26 ); version=unspecified <5.2.0.3.2 ( 2021/10/26 ); version=unspecified <5.2.0.4.2 ( 2021/10/26 )

Published CVSS scores

9.8NVDCVSS: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
7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1190Exploit 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

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Your stack

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