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Fencer Intel
critical 9.8

CVE-2021-28809 in the critical feed json

Missing Authentication for Critical Function in RTRR Server in HBS3

published 5y ago modified 4mo ago also EUVD-2021-15465

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
16.1%
EPSS 16.1% chance of exploitation in 30 days, percentile 96%
public exploits
0
none known

Summary

An improper access control vulnerability has been reported to affect certain legacy versions of HBS 3. If exploited, this vulnerability allows attackers to compromise the security of the operating system.QNAP have already fixed this vulnerability in the following versions of HBS 3: QTS 4.3.6: HBS 3 v3.0.210507 and later QTS 4.3.4: HBS 3 v3.0.210506 and later QTS 4.3.3: HBS 3 v3.0.210506 and later

Patch / fix

  • QNAP Systems Inc. HBS 3 v3.0.210506, v3.0.210507

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Exploit prediction

16.09% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 10.0 AV:N/AC:L/Au:N/C:C/I:C/A:C

Affected products

  • QNAP Systems Inc. HBS 3

Classification

Weakness
  • CWE-284 Improper Access Control
  • CWE-306 Missing Authentication for Critical Functionality
  • CWE-749 Exposed Dangerous Method or Function

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.