CVE-2021-28799 kev+ ransomware in the critical feed json
Improper Authorization Vulnerability in HBS 3 (Hybrid Backup Sync)
published 2021-05-13 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-15455
- cvss
- 10.0
- version 3.1, CNA
- cisa kev
- Exploited
- added 2022-03-31, used in ransomware
- epss
- 78.3%
- EPSS 78.3% chance of exploitation in 30 days, percentile 99.5%
- public exploits
- 0
- none known, plus a Nuclei check
Summary
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 .
Patch / fix
cisa required action Apply updates per vendor instructions.
- QNAP Systems Inc. HBS 3 v3.0.210411, v3.0.210412, v16.0.0415, v16.0.0419
Timeline
- Published
- Added to CISA KEV
- CISA patch deadline
- CISA SSVC: exploitation active
Known exploited
- Added
- 4 y ago
- Patch by
- 2022-04-21 (4 y ago)
- Ransomware
- Known to be used in ransomware campaigns
- Required action
- Apply updates per vendor instructions.
- Vendor, product
- QNAP, Network Attached Storage (NAS)
- CISA name
- QNAP NAS Improper Authorization Vulnerability
Ransomware
Groups reported to have exploited it in intrusions.
- eCh0raix ransomware gang
reported by unit42.paloaltonetworks.com
Ransomware Vulnerability Matrix by BushidoUK (github.com/BushidoUK/Ransomware-Vulnerability-Matrix), reformatted per CVE. CC BY 4.0
CISA SSVC
- Exploitation
- Active, exploited in the wild
- Automatable
- yes
- Technical impact
- total
- Assessed
- 21 mo ago
Exploit prediction
78.25% chance of exploitation in the next 30 days, higher than 99.5% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- Nuclei template QNAP HBS 3 - Broken Access Control nuclei detection template
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
| NVD | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVD | 2.0 | 7.5 | AV:N/AC:L/Au:N/C:P/I:P/A:P |
Affected products
- QNAP Systems Inc. HBS 3
- QNAP Systems Inc. HBS 2
- QNAP Systems Inc. HBS 1.3
Classification
- Weakness
-
- CWE-285 Improper Authorization
References
-
qnap.com
/en/security-advisory/QSA-21-13
vendor-advisory
-
cisa.gov
/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-28799
government-resource, us-government-resource
Sources
- CVE List CVE-2021-28799
- NVD CVE-2021-28799
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.