CVE-2021-28799
CWE-285
104.8
RPSRPS range: 0–105; KEV-listed vulnerabilities can receive an exploitation amplifier.
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 .
Source: NVD
Signals
- CVSS
- 10.0
- Critical · v3.1
- EPSS
- 78.25%
- Probability of exploitation in the next 30 days (FIRST)
- CISA KEV
- In CISA KEV since Mar 2022
- Fix commit
- No known fix commit
- Sources: MoreFixes, FreshFixes
- Weakness
- CWE-285
- Published
- 13 May 2021
- Last modified 3 Nov 2025
How to read these signals: RPS · EPSS · CISA KEV · Data sources
Get this score from the API
curl -H "Authorization: Bearer dsec_live_xxxxxxxx" \
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Data as of 7 Oct 2026, 05:16 UK time