SARA / Free Tools / CVE / CVE-2021-28799

CVE-2021-28799 — QNAP NAS Improper Authorization Vulnerability

An improper authorization vulnerability has been reported to affect QNAP NAS running HBS 3 (Hybrid Backup Sync. ) If exploited, the vulnerability allows remote attackers to log in to a device. This issue affects: QNAP Systems Inc. HBS 3 versions prior to v16.0.0415 on QTS 4.5.2;

CVSS
10.0 CRITICAL
EPSS
91.15% (top 0.40%)
CWE
CWE-285
Published
2021-05-13T02:55:13.827Z
Last modified
2025-10-21T23:25:45.551Z
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CISA KEV — Actively Exploited
Added to KEV
2022-03-31
BOD 22-01 due
2022-04-21
Ransomware use
Known

01What is this vulnerability?

An improper authorization vulnerability has been reported to affect QNAP NAS running HBS 3 (Hybrid Backup Sync. ) If exploited, the vulnerability allows remote attackers to log in to a device. This issue affects: QNAP Systems Inc. HBS 3 versions prior to v16.0.0415 on QTS 4.5.2; versions prior to v3.0.210412 on QTS 4.3.6; versions prior to v3.0.210411 on QTS 4.3.4; versions prior to v3.0.210411…

02Affected products

VendorProductVersions
QNAP Systems Inc.HBS 3unspecified
QNAP Systems Inc.HBS 3unspecified
QNAP Systems Inc.HBS 3unspecified
QNAP Systems Inc.HBS 3unspecified
QNAP Systems Inc.HBS 3unspecified
QNAP Systems Inc.HBS 3unspecified
QNAP Systems Inc.HBS 2all versions
QNAP Systems Inc.HBS 1.3all versions

03Active exploitation status

Yes — actively exploited. Added to the CISA KEV catalog on 2022-03-31. Ransomware use: Known.

04Recommended remediation

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection in your stack of choice:

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07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

09References

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