known ransomware use

QNAP NAS Improper Authorization Vulnerability

Added to KEV
2022-03-31
Federal due date
2022-04-21
Vendor
QNAP
Product
Network Attached Storage (NAS)
EPSS
99.7th percentile (score 0.924, as of 2026-06-08)
NVD CVSS v3.1
Ransomware use
Known
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2021-28799

CISA short description

QNAP NAS running HBS 3 contains an improper authorization vulnerability which can allow remote attackers to log in to a device.

Required action

Apply updates per vendor instructions.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.