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Vulnerabilities

Vulnerability · CVE-2023-39303

An improper authentication vulnerability has been reported to affect several QNAP operating system versions.

Published Feb 2, 2024 · catalog updated Jun 17, 2026 · An improper authentication vulnerability

Last checked Nov 7, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2023-39303. EPSS is 0.47%. Act only if a listed version of An improper authentication vulnerability is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (An improper authentication vulnerability).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Critical9.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.47%
Remediation
Advisory link
Affected products
cpe qnap/qts

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 QuTS hero h5.1.3.2578 build 20231110 and later QuTScloud c5.1.5.2651 and later

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe qnap/qts5.1.0.2348
  • cpe qnap/qts5.1.0.2399
  • cpe qnap/qts5.1.0.2418
  • cpe qnap/qts5.1.0.2444
  • cpe qnap/qts5.1.0.2466
  • cpe qnap/qts5.1.1.2491

How to fix CVE-2023-39303

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2023-39303. EPSS is 0.47%. Act only if a listed version of An improper authentication vulnerability is installed.

Which versions are affected?

Compare what you have installed with 5.1.0.2348, 5.1.0.2399, 5.1.0.2418, 5.1.0.2444, 5.1.0.2466, 5.1.1.2491. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-287: Improper Authentication. EPSS 0.47%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

QNAP QTS security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 2, 2024 · Monitored products — high

    Detected

    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 QuTS hero h5.1.3.2578 build 20231110 and later QuTScloud c5.1.5.2651 and later

  2. Jun 17, 2026 · Monitored products — high

    Updated

    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 QuTS hero h5.1.3.2578 build 20231110 and later QuTScloud c5.1.5.2651 and later

Sources

  • CVE.orgVulnerability recordCVE-2023-39303

    Official CVE identifier

    cve.org
  • Monitored products — highVendor advisoryCVE-2023-39303

    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 QuTS hero h5.1.3.2578 build 20231110 and later QuTScloud c5.1.5.2651 and later

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 6, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 7, 2026
  • Monitored products — highNov 6, 2026