CVE-2021-28806

lowpriority · track · 22EPSS 0.005 · 43 %ileEUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
0.51% (43rd) EPSS
CVSS 3.5 · low
Is it mine?
6 products
Check your exposure
Who says so?
3 sources
cnnvd · enisa_euvd · nvd

EPSS · scored 2026-10-28

A DOM-based XSS vulnerability has been reported to affect QNAP NAS running QTS and QuTS hero. If exploited, this vulnerability allows attackers to inject malicious code. This issue affects: QNAP Systems Inc. QTS versions prior to 4.5.3.1652 Build 20210428. QNAP Systems Inc. QuTS hero versions prior to h4.5.2.1638 Build 20210414. QNAP Systems Inc. QuTScloud versions prior to c4.5.5.1656 Build 20210503. This issue does not affect: QNAP Systems Inc. QTS 4.3.6; 4.3.3.

01

cvss

Technical severity, 0–10. One row per scoring source.

5.7
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 3.5–5.7

v2.03.5lowAV:N/AC:M/Au:S/C:N/I:P/A:Nprimary · NVD / NIST USexploitability 6.8 · impact 2.9
v3.15.4mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:Nprimary · NVD / NIST USexploitability 2.3 · impact 2.7
v3.15.7mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:Nsecondary · ENISA EU
v3.15.7mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:Nsecondary · security@qnapsecurity.com.twexploitability 2.1 · impact 3.6
v3.15mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)
02

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-79US
03

affected products (6)

Products and version ranges known to be affected.

04

also known as (3)

Other names and identifiers for this entity.

05

sources

Which sources assert this record, and when.

cnnvdenisa_euvdnvdNVDCVE.orgMITRE
published 2021-06-03modified 2026-06-17
06

references (7)

External citations — patches, advisories, analysis.

scry

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