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Vulnerability record · CVE-2021-38687 · published 29 December 2021

CVE-2021-38687: Qnap surveillance station classic buffer overflow vulnerability

Qnap · Surveillance Station

A stack buffer overflow vulnerability has been reported to affect QNAP NAS running Surveillance Station. If exploited, this vulnerability allows attackers to execute arbitrary code. We have already fixed this vulnerability in the following versions of Surveillance Station: QTS 5.0.0 (64 bit): Surveillance Station 5.2.0.4.2 ( 2021/10/26 ) and later QTS 5.0.0 (32 bit): Surveillance Station 5.2.0.3.2 ( 2021/10/26 ) and later QTS 4.3.6 (64 bit): Surveillance Station 5.1.5.4.6 ( 2021/10/26 ) and later QTS 4.3.6 (32 bit): Surveillance Station 5.1.5.3.6 ( 2021/10/26 ) and later QTS 4.3.3: Surveillance Station 5.1.5.3.6 ( 2021/10/26 ) and later

9.8 CVSS 3.1 Critical EPSS 1.3% · top 31.1% CWE-120 · Classic buffer overflow
9.8CVSS 3.1 base score, v2 7.5
1.3%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

A stack buffer overflow vulnerability has been reported to affect QNAP NAS running Surveillance Station. If exploited, this vulnerability allows attackers to execute arbitrary code. We have already fixed this vulnerability in the following versions of Surveillance Station: QTS 5.0.0 (64 bit): Surveillance Station 5.2.0.4.2 ( 2021/10/26 ) and later QTS 5.0.0 (32 bit): Surveillance Station 5.2.0.3.2 ( 2021/10/26 ) and later QTS 4.3.6 (64 bit): Surveillance Station 5.1.5.4.6 ( 2021/10/26 ) and later QTS 4.3.6 (32 bit): Surveillance Station 5.1.5.3.6 ( 2021/10/26 ) and later QTS 4.3.3: Surveillance Station 5.1.5.3.6 ( 2021/10/26 ) and later

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://www.qnap.com/en/security-advisory/qsa-21-46 Vendor Advisory
https://www.qnap.com/en/security-advisory/qsa-21-46 Vendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-38687), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.