How severe is CVE-2025-66280?

CVE-2025-66280 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-2025-66280 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66280?

CVE-2025-66280 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-2025-66280?

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-2025-66280 have an EU (EUVD) identifier?

Yes. CVE-2025-66280 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-210101.

When was CVE-2025-66280 published?

CVE-2025-66280 was published on 2026-06-10 and last updated on 2026-06-17.

CVE-2025-66280

CVE-2025-66280 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-121.

Key facts

Severity: High (CVSS 3.x base score 7.2)
CVSS v4: 5.1
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-210101
Weakness: CWE-121
Affected product: Qnap Qts
Published: 2026-06-10
Last modified: 2026-06-17

Description

An integer overflow or wraparound vulnerability has been reported to affect several QNAP operating system versions. If a remote attacker gains an administrator account, they can then exploit the vulnerability to compromise the security of the system. 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-2025-66280?: An integer overflow or wraparound vulnerability has been reported to affect several QNAP operating system versions. If a remote attacker gains an administrator account, they can then exploit the vulnerability to compromise the security of the system. 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-2025-66280?: CVE-2025-66280 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-2025-66280 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66280?: CVE-2025-66280 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-2025-66280?: 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-2025-66280 have an EU (EUVD) identifier?: Yes. CVE-2025-66280 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-210101.
When was CVE-2025-66280 published?: CVE-2025-66280 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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