CVE-2025-66277
Remote path traversal in QNAP OS enables access to unintended filesystem paths.
Is CVE-2025-66277 being exploited?
Not confirmed. CVE-2025-66277 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 0.66% probability of exploitation in the next 30 days.
How severe is CVE-2025-66277?
CVE-2025-66277 is rated Critical with a CVSS score of 9.2. 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-2025-66277?
Yes. A fix has been recorded for CVE-2025-66277. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2025-66277 affect?
CVE-2025-66277 affects QTS 5.2.8.3350+ (build 20251216 and later), QuTS hero h5.3.2.3354+ (build 20251225 and later), QuTS hero h5.2.8.3350+ (build 20251216 and later). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2025-66277?
Upgrade to fixed builds: QTS 5.2.8.3350+; QuTS hero h5.2.8.3350+ / h5.3.2.3354+.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote path traversal allows reading arbitrary files, exposing sensitive data.
Immediate action required
- affected>= 5.2.x and < 5.2.8.3350 build 20251216
- affected>= h5.3.x and < h5.3.2.3354 build 20251225
- affected>= h5.2.x and < h5.2.8.3350 build 20251216
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.