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PatchSiren cyber security CVE debrief

CVE-2026-41539 QNAP Systems Inc. CVE debrief

A high-severity cross-site scripting (XSS) vulnerability, tracked as CVE-2026-41539, has been reported in several QNAP operating system versions. This vulnerability enables remote attackers to bypass security mechanisms or read application data. The Common Vulnerability Scoring System (CVSS) score for this vulnerability is 8.7, indicating a high level of severity. QNAP has addressed the vulnerability in the following versions: QTS 5.2.9.3492 build 20260507 and later, QuTS hero h5.2.9.3499 build 20260514 and later, QuTS hero h5.3.4.3500 build 20260520 and later, and QuTS hero h6.0.0.3500 build 20260520 and later.

Vendor
QNAP Systems Inc.
Product
QTS
CVSS
MEDIUM 6.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-09
Original CVE updated
2026-06-30
Advisory published
2026-06-09
Advisory updated
2026-06-30

Who should care

CVE-2026-41539 affects users of QNAP operating systems, particularly those using versions prior to the patched releases. System administrators and users of QNAP devices should assess their current version and update to a patched version if necessary.

Technical summary

The vulnerability is a cross-site scripting (XSS) issue, which occurs when user input is not properly sanitized. This allows an attacker to inject malicious scripts into the application, potentially leading to unauthorized actions or data exposure. The CVSS vector for this vulnerability is CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X.

Defensive priority

High

Recommended defensive actions

  • Update to QTS 5.2.9.3492 build 20260507 or later
  • Update to QuTS hero h5.2.9.3499 build 20260514 or later
  • Update to QuTS hero h5.3.4.3500 build 20260520 or later
  • Update to QuTS hero h6.0.0.3500 build 20260520 or later

Evidence notes

The CVE-2026-41539 vulnerability has been analyzed and verified by official sources, including the National Vulnerability Database (NVD).

Sources and references

Verified primary and authoritative sources

  • CVE-2026-41539 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-41539

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-41539 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-41539

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.