How severe is CVE-2024-21899?

CVE-2024-21899 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-2024-21899 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 24% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2024-21899?

CVE-2024-21899 primarily affects Qnap Qts. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2024-21899?

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-2024-21899 have an EU (EUVD) identifier?

Yes. CVE-2024-21899 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-19510.

When was CVE-2024-21899 published?

CVE-2024-21899 was published on 2024-03-08 and last updated on 2026-06-17.

CVE-2024-21899

CVE-2024-21899 is a critical-severity vulnerability in Qnap Qts with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 24% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-287.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 24% (98th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2024-19510
Weakness: CWE-287
Affected product: Qnap Qts
Published: 2024-03-08
Last modified: 2026-06-17

Description

An improper authentication vulnerability has been reported to affect several QNAP operating system versions. If exploited, the vulnerability could allow users to compromise the security of the system via a network. We have already fixed the vulnerability in the following versions: QTS 5.1.3.2578 build 20231110 and later QTS 4.5.4.2627 build 20231225 and later QuTS hero h5.1.3.2578 build 20231110 and later QuTS hero h4.5.4.2626 build 20231225 and later QuTScloud c5.1.5.2651 and later

Frequently asked questions

What is CVE-2024-21899?: An improper authentication vulnerability has been reported to affect several QNAP operating system versions. If exploited, the vulnerability could allow users to compromise the security of the system via a network. We have already fixed the vulnerability in the following versions: QTS 5.1.3.2578 build 20231110 and later QTS 4.5.4.2627 build 20231225 and later QuTS hero h5.1.3.2578 build 20231110 and later QuTS hero h4.5.4.2626 build 20231225 and later QuTScloud c5.1.5.2651 and later
How severe is CVE-2024-21899?: CVE-2024-21899 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-2024-21899 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 24% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2024-21899?: CVE-2024-21899 primarily affects Qnap Qts. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2024-21899?: 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-2024-21899 have an EU (EUVD) identifier?: Yes. CVE-2024-21899 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-19510.
When was CVE-2024-21899 published?: CVE-2024-21899 was published on 2024-03-08 and last updated on 2026-06-17.

References

https://www.qnap.com/en/security-advisory/qsa-24-09

Affected products (7)

cpe:2.3:o:qnap:qts:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:4.5.4.2627:-:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.1.3.2578:-:*:*:*:*:*:*
cpe:2.3:o:qnap:quts_hero:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:quts_hero:h4.5.4.2626:-:*:*:*:*:*:*
cpe:2.3:o:qnap:quts_hero:h5.1.3.2578:-:*:*:*:*:*:*
cpe:2.3:o:qnap:qutscloud:*:*:*:*:*:*:*:*

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Other CWE-287 (Improper Authentication) vulnerabilities

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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…

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