Unrated severityCISA KEVNVD Advisory· Published May 13, 2021· Updated Oct 21, 2025
Improper Authorization Vulnerability in HBS 3 (Hybrid Backup Sync)
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 .
Affected products
3- QNAP Systems Inc./HBS 3v5Range: unspecified
- QNAP Systems Inc./HBS 2v5Range: all versions
- QNAP Systems Inc./HBS 1.3v5Range: all versions
Patches
0No patches discovered yet.
Vulnerability mechanics
AI mechanics synthesis has not run for this CVE yet.
References
1- www.qnap.com/en/security-advisory/QSA-21-13mitrex_refsource_MISC
News mentions
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