How severe is CVE-2025-66281?

CVE-2025-66281 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2025-66281 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66281?

CVE-2025-66281 primarily affects Qnap Qts. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-66281?

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.

Does CVE-2025-66281 have an EU (EUVD) identifier?

Yes. CVE-2025-66281 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-210102.

When was CVE-2025-66281 published?

CVE-2025-66281 was published on 2026-06-10 and last updated on 2026-06-17.

CVE-2025-66281

CVE-2025-66281 is a high-severity vulnerability in Qnap Qts with a CVSS 3.x base score of 7.2. 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-476.

Key facts

Severity: High (CVSS 3.x base score 7.2)
CVSS v4: 6.9
EPSS exploit prediction: 0% (36th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-210102
Weakness: CWE-476
Affected product: Qnap Qts
Published: 2026-06-10
Last modified: 2026-06-17

Description

A NULL pointer dereference vulnerability has been reported to affect several QNAP operating system versions. The remote attackers can then exploit the vulnerability to launch a denial-of-service (DoS) attack. We have already fixed the vulnerability in the following versions: QTS 5.2.9.3410 build 20260214 and later QuTS hero h5.2.9.3410 build 20260214 and later QuTS hero h5.3.4.3500 build 20260520 and later QuTS hero h6.0.0.3397 build 20260206 and later

Frequently asked questions

What is CVE-2025-66281?: A NULL pointer dereference vulnerability has been reported to affect several QNAP operating system versions. The remote attackers can then exploit the vulnerability to launch a denial-of-service (DoS) attack. We have already fixed the vulnerability in the following versions: QTS 5.2.9.3410 build 20260214 and later QuTS hero h5.2.9.3410 build 20260214 and later QuTS hero h5.3.4.3500 build 20260520 and later QuTS hero h6.0.0.3397 build 20260206 and later
How severe is CVE-2025-66281?: CVE-2025-66281 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2025-66281 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66281?: CVE-2025-66281 primarily affects Qnap Qts. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-66281?: 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.
Does CVE-2025-66281 have an EU (EUVD) identifier?: Yes. CVE-2025-66281 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-210102.
When was CVE-2025-66281 published?: CVE-2025-66281 was published on 2026-06-10 and last updated on 2026-06-17.

References

https://www.qnap.com/en/security-advisory/qsa-26-10

Affected products (2)

cpe:2.3:o:qnap:qts:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:quts_hero:*:*:*:*:*:*:*:*

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