How severe is CVE-2021-28799?

CVE-2021-28799 has a CVSS 3.1 base score of 10 (CRITICAL). EPSS estimates a 78.3% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

CVE-2021-28799: Improper Authorization Vulnerability in HBS 3 (Hybrid

CISA Known Exploited Vulnerabilities

QNAP NAS Improper Authorization Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV

2022-03-31

Remediation due

2022-04-21

Ransomware

Known use

Required action
Apply updates per vendor instructions.

CISA notes
https://nvd.nist.gov/vuln/detail/CVE-2021-28799

Description

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 on QTS 4.3.3; versions prior to v16.0.0419 on QuTS hero h4.5.1; versions prior to v16.0.0419 on QuTScloud c4.5.1~c4.5.4. This issue does not affect: QNAP Systems Inc. HBS 2 . QNAP Systems Inc. HBS 1.3 .

Severity

CVSS 3.1 · CNA10 CRITICAL

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

SSVC · CISA-ADP

Exploitationactive

Automatableyes

Technical impacttotal

Affected Products

Vendor	Product	Affected versions
QNAP Systems Inc.	HBS 3	unspecified to <v16.0.0415
QNAP Systems Inc.	HBS 3	unspecified to <v3.0.210412
QNAP Systems Inc.	HBS 3	unspecified to <v3.0.210411
QNAP Systems Inc.	HBS 3	unspecified to <v3.0.210411
QNAP Systems Inc.	HBS 3	unspecified to <v16.0.0419
QNAP Systems Inc.	HBS 3	unspecified to <v16.0.0419
QNAP Systems Inc.	HBS 2	all versions (unaffected)
QNAP Systems Inc.	HBS 1.3	all versions (unaffected)

References

1 Links

Other references

https://www.qnap.com/en/security-advisory/QSA-21-13

Record Details

Published

2021-05-13

Last updated

2025-10-21

Assigner (CNA)

qnap

Credited to

ZUSO ART

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Related Tool Categories

Tool categories that test for or protect against this vulnerability class.

CWE-285 · Improper Authorization

IAM Tools Application Security Tools

CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.