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Vulnerabilities

Vulnerability · CVE-2025-66277

A link following vulnerability has been reported to affect several QNAP operating system versions.

Published Feb 11, 2026 · catalog updated Jun 17, 2026 · A link following vulnerability

Last checked Nov 6, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2025-66277. EPSS is 0.71%. Act only if a listed version of A link following 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 (A link following vulnerability).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Critical9.2
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.71%
Remediation
Version ranges on file
Affected products
cpe qnap/qts · vendor QNAP Systems Inc. QuTS hero h5.3.x <h5.3.2.3354 build 20251225

A link following vulnerability has been reported to affect several QNAP operating system versions. The remote attackers can then exploit the vulnerability to traverse the file system to unintended locations. We have already fixed the vulnerability in the following versions: 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

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/qts5.2.0.2737
  • cpe qnap/qts5.2.0.2744
  • cpe qnap/qts5.2.0.2782
  • cpe qnap/qts5.2.0.2802
  • cpe qnap/qts5.2.0.2823
  • cpe qnap/qts5.2.0.2851
  • vendor QNAP Systems Inc. QuTS hero h5.3.x <h5.3.2.3354 build 20251225h5.3.x <h5.3.2.3354 build 20251225

How to fix CVE-2025-66277

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-2025-66277. EPSS is 0.71%. Act only if a listed version of A link following vulnerability is installed.

Which versions are affected?

Compare what you have installed with QNAP Systems Inc. QuTS hero h5.3.x <h5.3.2.3354 build 20251225 h5.3.x <h5.3.2.3354 build 20251225. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-59: Link Following. EPSS 0.71%. 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 11, 2026 · EUVD

    Detected

    A link following vulnerability has been reported to affect several QNAP operating system versions. The remote attackers can then exploit the vulnerability to traverse the file system to unintended locations. We have already fixed the vulnerability in the following versions: 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 a

  2. Feb 26, 2026 · EUVD

    Updated

    A link following vulnerability has been reported to affect several QNAP operating system versions. The remote attackers can then exploit the vulnerability to traverse the file system to unintended locations. We have already fixed the vulnerability in the following versions: 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 a

  3. Jun 17, 2026 · Monitored products — high

    Updated

    A link following vulnerability has been reported to affect several QNAP operating system versions. The remote attackers can then exploit the vulnerability to traverse the file system to unintended locations. We have already fixed the vulnerability in the following versions: 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 a

Sources

  • CVE.orgVulnerability recordCVE-2025-66277

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-66277

    30-day exploitation probability 0.71%

    first.org
  • EUVDVulnerability recordEUVD-2025-207017

    A link following vulnerability has been reported to affect several QNAP operating system versions. The remote attackers can then exploit the vulnerability to traverse the file system to unintended locations. We have already fixed the vulnerability in the following versions: QTS 5

    euvd.enisa.europa.eu
  • Monitored products — highVendor advisoryCVE-2025-66277

    A link following vulnerability has been reported to affect several QNAP operating system versions. The remote attackers can then exploit the vulnerability to traverse the file system to unintended locations. We have already fixed the vulnerability in the following versions: 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 a

    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.

  • Monitored products — highNov 6, 2026
  • FIRST EPSSNov 6, 2026
  • CVE.orgNov 4, 2026
  • EUVDNov 2, 2026