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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 .

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

Affected products

4
  • Qnap/HBS 3llm-create
  • QNAP Systems Inc./HBS 1.3v5
    Range: all versions
  • QNAP Systems Inc./HBS 2v5
    Range: all versions
  • QNAP Systems Inc./HBS 3v5
    Range: unspecified

Patches

Vulnerability mechanics

References

1

News mentions

0

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