CVE-2021-28799
Improper Authorization Vulnerability in HBS 3 (Hybrid Backup Sync)
KEV RANSOMWARECRITICAL 9.8EPSS 78.2%
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 .
- Affected
- QNAP Systems Inc. · HBS 3 · HBS 2 · HBS 1.3
- CVSS v3.1 NVD
- 9.8 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS v3.1 QNAPSECURITY
- 10.0 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H - CVSS v2.0 NVD
- 7.5 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P - EPSS
- 78.25% chance of exploitation in the next 30 days, 100th percentile
- CISA KEV
- added 2022-03-31, used in ransomware campaigns
- Nuclei
- critical · CWE-285
- Published
- 2021-05-13
- Updated
- 2025-10-21