How severe is CVE-2021-28807?

CVE-2021-28807 has a CVSS 3.x base score of 7.7, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-28807 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (69th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-28807?

CVE-2021-28807 affects Qnap Q'center. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-28807?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-28807 published?

CVE-2021-28807 was published on 2021-06-03 and last updated on 2026-06-17.

CVE-2021-28807

CVE-2021-28807 is a high-severity vulnerability in Qnap Q'center with a CVSS 3.x base score of 7.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: High (CVSS 3.x base score 7.7)
CVSS v2: 3.5
EPSS exploit prediction: 1% (69th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Qnap Q'center
Published: 2021-06-03
Last modified: 2026-06-17

Description

A post-authentication reflected XSS vulnerability has been reported to affect QNAP NAS running Q’center. If exploited, this vulnerability allows remote attackers to inject malicious code. QNAP have already fixed this vulnerability in the following versions of Q’center: QTS 4.5.3: Q’center v1.12.1012 and later QTS 4.3.6: Q’center v1.10.1004 and later QTS 4.3.3: Q’center v1.10.1004 and later QuTS hero h4.5.2: Q’center v1.12.1012 and later QuTScloud c4.5.4: Q’center v1.12.1012 and later

Frequently asked questions

What is CVE-2021-28807?: A post-authentication reflected XSS vulnerability has been reported to affect QNAP NAS running Q’center. If exploited, this vulnerability allows remote attackers to inject malicious code. QNAP have already fixed this vulnerability in the following versions of Q’center: QTS 4.5.3: Q’center v1.12.1012 and later QTS 4.3.6: Q’center v1.10.1004 and later QTS 4.3.3: Q’center v1.10.1004 and later QuTS hero h4.5.2: Q’center v1.12.1012 and later QuTScloud c4.5.4: Q’center v1.12.1012 and later
How severe is CVE-2021-28807?: CVE-2021-28807 has a CVSS 3.x base score of 7.7, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-28807 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (69th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-28807?: CVE-2021-28807 affects Qnap Q'center. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-28807?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-28807 published?: CVE-2021-28807 was published on 2021-06-03 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:qnap:q\'center:*:*:*:*:*:*:*:*

More vulnerabilities in Qnap Q'center

CVE-2018-0710 — High (CVSS 8.8): Command injection vulnerability in SSH of QNAP Q'center Virtual Appliance version 1.7.1063 and earlier could allow…
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