CVE-2026-41539
XSS in QNAP OS allows data access and security bypass via web UI.
Is CVE-2026-41539 being exploited?
Not confirmed. CVE-2026-41539 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.19% probability of exploitation in the next 30 days.
How severe is CVE-2026-41539?
CVE-2026-41539 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-41539?
Yes. A fix has been recorded for CVE-2026-41539. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-41539 affect?
CVE-2026-41539 affects 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, QuTS hero h6.0.0.3500 build 20260520 and later. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-41539?
Upgrade to fixed QTS/QuTS builds.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote XSS can read app data and bypass security checks in QTS/QuTS web UI.
Patch when possible
- affected>= 5.2.0 and < 5.2.9.3492 build 20260507
- affected>= h5.2.0 and < h5.2.9.3499 build 20260514
- affected>= h5.3.0 and < h5.3.4.3500 build 20260520
- affected>= ? and < h6.0.0.3500 build 20260520
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.