CVE-2021-28799 (GCVE-0-2021-28799)
Vulnerability from cvelistv5 – Published: 2021-05-13 02:55 – Updated: 2025-10-21 23:25- CWE-285 - Improper Authorization
| URL | Tags |
|---|---|
| https://www.qnap.com/en/security-advisory/QSA-21-13 | x_refsource_MISC |
| https://www.cisa.gov/known-exploited-vulnerabilit… | government-resource |
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| QNAP Systems Inc. | HBS 3 |
Affected:
unspecified , < v16.0.0415
(custom)
|
guessed | |
| QNAP Systems Inc. | HBS 3 |
Affected:
unspecified , < v3.0.210412
(custom)
|
guessed | |
| QNAP Systems Inc. | HBS 3 |
Affected:
unspecified , < v3.0.210411
(custom)
|
guessed | |
| QNAP Systems Inc. | HBS 3 |
Affected:
unspecified , < v16.0.0419
(custom)
|
guessed | |
| QNAP Systems Inc. | HBS 2 |
Unaffected:
all versions
|
guessed | |
| QNAP Systems Inc. | HBS 1.3 |
Unaffected:
all versions
|
guessed |
CISA
Known Exploited Vulnerability - GCVE BCP-07 Compliant
Exploited: Yes
Timestamps
Scope
Evidence
Type: Vendor Report
Signal: Successful Exploitation
Confidence: 80%
Source: cisa-kev
Details
| Cwes | CWE-285 |
|---|---|
| Feed | CISA Known Exploited Vulnerabilities Catalog |
| Product | Network Attached Storage (NAS) |
| Due Date | 2022-04-21 |
| Date Added | 2022-03-31 |
| Vendorproject | QNAP |
| Vulnerabilityname | QNAP NAS Improper Authorization Vulnerability |
| Knownransomwarecampaignuse | Known |
References
Shadowserver
Known Exploited Vulnerability - GCVE BCP-07 Compliant
Exploited: Yes
Characteristics
Timestamps
Scope
Evidence
Type: Honeypot
Signal: In The Wild Attempts
Confidence: 70%
Source: shadowserver
Details
| 1D | 2 |
|---|---|
| Iot | yes |
| Feed | Shadowserver Foundation honeypot/exploited-vulnerabilities |
| Type | http-scan |
| Class | nas |
| 7D Avg | 0 |
| Vendor | QNAP |
| 30D Avg | 2 |
| 90D Avg | 2 |
| Product | QNAP NAS running HBS 3 |
| Cisa Kev | yes |
| Connections | 3 |
| Observation Date | 2026-11-10 |
| Vulnerability Class | CVSS |
| Vulnerability Score | 9.8 |
| Vulnerability Severity | Critical |
References
Previdian
Known Exploited Vulnerability - GCVE BCP-07 Compliant
Exploited: Yes
Timestamps
Scope
Evidence
Type: Public Report
Signal: Confirmed Compromise
Confidence: 70%
Source: kevintel
Details
| Feed | KEVIntel (kevintel.com) |
|---|---|
| Title | Improper Authorization Vulnerability in HBS 3 (Hybrid Backup Sync) |
| Vendor | QNAP Systems Inc. |
| Product | HBS 3, HBS 2, HBS 1.3 |
| Added Date | 2022-03-31T00:00:00.000Z |
| Cvss Score | 10.0 |
| Epss Score | None |
| Cvss Severity | CRITICAL |
| Epss Percentile | None |
| Used In Malware | yes |
| Ahead Of Cisa Kev | None |
| Not Yet In Cisa Kev | False |
References
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"value": "QNAP have already fixed this vulnerability in the following versions of HBS 3:\nQTS 4.5.2: HBS 3 v16.0.0415 and later\nQTS 4.3.6: HBS 3 v3.0.210412 and later\nQTS 4.3.3 and 4.3.4: HBS 3 v3.0.210411 and later\nQuTS hero h4.5.1: HBS 3 v16.0.0419 and later\nQuTScloud c4.5.1~c4.5.4: HBS 3 v16.0.0419 and later"
}
],
"source": {
"advisory": "QSA-21-13",
"discovery": "EXTERNAL"
}
}
}
},
"cveMetadata": {
"assignerOrgId": "2fd009eb-170a-4625-932b-17a53af1051f",
"assignerShortName": "qnap",
"cveId": "CVE-2021-28799",
"datePublished": "2021-05-13T02:55:13.827Z",
"dateReserved": "2021-03-18T00:00:00.000Z",
"dateUpdated": "2025-10-21T23:25:45.551Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.1"
}
}
}
Solutions
Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
How durations are calculated
Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.
Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.