What is CVE-2021-28809?

CVE-2021-28809 is a critical-severity vulnerability in QNAP Hybrid Backup Sync, classified under Improper Access Control. CVSS score: 9.8/10. Published 2021-07-08.

How severe is CVE-2021-28809?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in QNAP Hybrid Backup Sync

CVE-2021-28809

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

EPSS: 0.158 (96.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Qnap Hybrid_backup_sync
Qnap Qts — versions 4.3.6, 4.3.4, 4.3.3
Qnap Systems Inc. Hbs 3 — versions unspecified

Weakness classification (CWE)

References

security@qnapsecurity.com.tw (x_refsource_MISC, Vendor Advisory)
security@qnapsecurity.com.tw (VDB Entry, Third Party Advisory, x_refsource_MISC)

Frequently asked questions

What is CVE-2021-28809?: CVE-2021-28809 is a critical-severity vulnerability in QNAP Hybrid Backup Sync, classified under Improper Access Control. CVSS score: 9.8/10. Published 2021-07-08.
How severe is CVE-2021-28809?: Critical severity. CVSS v3 base score is 9.8 out of 10.