How severe is CVE-2021-38686?

CVE-2021-38686 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-38686 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-38686?

CVE-2021-38686 affects Qnap Qvr. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-38686?

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-2021-38686 published?

CVE-2021-38686 was published on 2021-11-26 and last updated on 2026-06-17.

CVE-2021-38686

CVE-2021-38686 is a high-severity vulnerability in Qnap Qvr with a CVSS 3.x base score of 8.8. 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: High (CVSS 3.x base score 8.8)
CVSS v2: 6.8
EPSS exploit prediction: 1% (57th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Qnap Qvr
Published: 2021-11-26
Last modified: 2026-06-17

Description

An improper authentication vulnerability has been reported to affect QNAP device, VioStor. If exploited, this vulnerability allows attackers to compromise the security of the system. We have already fixed this vulnerability in the following versions of QVR: QVR FW 5.1.6 build 20211109 and later

Frequently asked questions

What is CVE-2021-38686?: An improper authentication vulnerability has been reported to affect QNAP device, VioStor. If exploited, this vulnerability allows attackers to compromise the security of the system. We have already fixed this vulnerability in the following versions of QVR: QVR FW 5.1.6 build 20211109 and later
How severe is CVE-2021-38686?: CVE-2021-38686 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-38686 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-38686?: CVE-2021-38686 affects Qnap Qvr. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-38686?: 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-2021-38686 published?: CVE-2021-38686 was published on 2021-11-26 and last updated on 2026-06-17.

References

https://www.qnap.com/en/security-advisory/qsa-21-52

Affected products (1)

cpe:2.3:a:qnap:qvr:*:*:*:*:*:*:*:*

More vulnerabilities in Qnap Qvr

CVE-2025-52856 — Critical (CVSS 9.8): An improper authentication vulnerability has been reported to affect VioStor. If a remote attacker, they can then…
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-2021-34352 — High (CVSS 7.2): A command injection vulnerability has been reported to affect QNAP device running QVR. If exploited, this vulnerability…

All CVEs affecting Qnap Qvr →

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 →