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
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.161 (96.9th percentile), scored .
Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 97th percentile — 96.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.161 · newest: 0.161 · change: 0.000
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
- www.qnap.com/en/security-advisory/qsa-21-19 (Vendor Advisory)
- www.zerodayinitiative.com/advisories/ZDI-21-783/ (VDB Entry, Third Party Advisory)
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.