CVE-2021-28809

Exploitation

Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.

SSVC decision

Not assessed by CISA

EPSS probability

15.80% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 96.6% of scored records. A rank, not a probability.

NVD base score

9.8 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

NVD analysis status

Modified. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2021-07-08 07:40Z5 YR AGO

Last updated

2024-09-17 00:36Z1 YR AGO

Reserved

2021-03-18

Assigning CNA

qnap

Record state

PUBLISHED

Severity

Critical (CVSS 9.8)

CNA CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weaknesses

• CWE-284Improper Access ControlPillar
• CWE-306Missing Authentication for Critical FunctionBase
• CWE-749Exposed Dangerous Method or FunctionBase

Data version

5.1

Document digest

c8e73ab62af009f8c1f3b282a5f8f8ce264ce7fd58da1fbd741dfea2a6ea950e

• www.qnap.comhttps://www.qnap.com/en/security-advisory/qsa-21-19x_refsource_MISC
• www.zerodayinitiative.comhttps://www.zerodayinitiative.com/advisories/ZDI-21-783/x_refsource_MISC