How severe is CVE-2025-52856?

CVE-2025-52856 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2025-52856 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-52856?

CVE-2025-52856 primarily affects Qnap Qvr. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-52856?

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

Does CVE-2025-52856 have an EU (EUVD) identifier?

Yes. CVE-2025-52856 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-26252.

When was CVE-2025-52856 published?

CVE-2025-52856 was published on 2025-08-29 and last updated on 2026-06-17.

CVE-2025-52856

CVE-2025-52856 is a critical-severity vulnerability in Qnap Qvr with a CVSS 3.x base score of 9.8. 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-287.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v4: 9.3
EPSS exploit prediction: 1% (45th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-26252
Weakness: CWE-287
Affected product: Qnap Qvr
Published: 2025-08-29
Last modified: 2026-06-17

Description

An improper authentication vulnerability has been reported to affect VioStor. If a remote attacker, they can then exploit the vulnerability to compromise the security of the system. We have already fixed the vulnerability in the following version: VioStor 5.1.6 build 20250621 and later

Frequently asked questions

What is CVE-2025-52856?: An improper authentication vulnerability has been reported to affect VioStor. If a remote attacker, they can then exploit the vulnerability to compromise the security of the system. We have already fixed the vulnerability in the following version: VioStor 5.1.6 build 20250621 and later
How severe is CVE-2025-52856?: CVE-2025-52856 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2025-52856 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-52856?: CVE-2025-52856 primarily affects Qnap Qvr. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-52856?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2025-52856 have an EU (EUVD) identifier?: Yes. CVE-2025-52856 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-26252.
When was CVE-2025-52856 published?: CVE-2025-52856 was published on 2025-08-29 and last updated on 2026-06-17.

References

https://www.qnap.com/en/security-advisory/qsa-25-29

Affected products (2)

cpe:2.3:a:qnap:qvr:*:*:*:*:*:*:*:*
cpe:2.3:a:qnap:qvr:5.1.6:-:*:*:*:*:*:*

More vulnerabilities in Qnap Qvr

CVE-2022-27588 — Critical (CVSS 9.8): We have already fixed this vulnerability in the following versions of QVR: QVR 5.1.6 build 20220401 and later
CVE-2021-38685 — Critical (CVSS 9.8): A command injection vulnerability has been reported to affect QNAP device, VioStor. If exploited, this vulnerability…
CVE-2021-34351 — Critical (CVSS 9.8): A command injection vulnerability has been reported to affect QNAP device running QVR. If exploited, this vulnerability…
CVE-2021-34348 — Critical (CVSS 9.8): A command injection vulnerability has been reported to affect QNAP device running QVR. If exploited, this vulnerability…
CVE-2021-38686 — High (CVSS 8.8): An improper authentication vulnerability has been reported to affect QNAP device, VioStor. If exploited, this…
CVE-2021-34352 — High (CVSS 7.2): A command injection vulnerability has been reported to affect QNAP device running QVR. If exploited, this vulnerability…

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Other CWE-287 (Improper Authentication) vulnerabilities

CVE-2026-45480 — Critical (CVSS 10.0): Improper authentication in Azure Active Directory allows an unauthorized attacker to elevate privileges over a network.
CVE-2026-46389 — Critical (CVSS 10.0): UDS Identity Config builds the Keycloak configuration image (realm, plugins, theme, truststore, JARs) consumed by UDS…
CVE-2026-10611 — Critical (CVSS 10.0): An authentication bypass vulnerability exists in MISP when LDAP mixed authentication is enabled with OTP enforcement.…
CVE-2026-47280 — Critical (CVSS 10.0): Improper authentication in Azure Resource Manager (ARM) allows an unauthorized attacker to elevate privileges over a…
CVE-2026-42822 — Critical (CVSS 10.0): Improper authentication in Azure Local Disconnected Operations allows an unauthorized attacker to elevate privileges…
CVE-2026-20182 — Critical (CVSS 10.0): May 2026: This security advisory provides the details and fix information for a vulnerability that was discovered and…

Browse all CWE-287 (Improper Authentication) vulnerabilities →