Critical severity · published Feb 11, 2026
CVE-2025-66277
A link following vulnerability has been reported to affect several QNAP operating system versions
9.8
CVSS
0.7%
EPSS
No
On KEV
Description
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
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 53% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
QT
Qts · Qnap
5.2.0.2737; 5.2.0.2744; 5.2.0.2782; 5.2.0.2802; 5.2.0.2823; 5.2.0.2851; +13 more · source: NVD
QH
Quts Hero · Qnap
h5.2.0.2737; h5.2.0.2782; h5.2.0.2789; h5.2.0.2802; h5.2.0.2823; h5.2.0.2851; +12 more · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-66277
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-66277
Vendor Advisory
https://www.qnap.com/en/security-advisory/qsa-26-05
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