Is CVE-2021-28806 in the CISA KEV catalog?

No. CVE-2021-28806 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-28806?

CVE-2021-28806 has a CVSS v3 base score of 5.7 (MEDIUM).

What is the EPSS score for CVE-2021-28806?

CVE-2021-28806 has an EPSS score of 0.51% (39th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-28806?

Upgrade qts to 4.5.3.1652 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2021-28806

MEDIUM

5.7

CVSS v3

NVD

Description

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.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

qtsNVD

Affected:< 4.5.3.1652Fixed in:4.5.3.1652CVE-2021-28806derived from NVD

quts heroNVD

Affected:< h4.5.2.1638Fixed in:h4.5.2.1638CVE-2021-28806derived from NVD

qutscloudNVD

Affected:< c4.5.5.1656Fixed in:c4.5.5.1656CVE-2021-28806derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

0.51%probability of exploitation in 30 days

39thpercentile

Low risk: more likely to be exploited than 39% of all known CVEs.

References

Vendor Advisory1

qnap.com

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.