CVE-2025-66277: QNAP Systems QTS · CWE-59
Affects QNAP Systems QTSSource CVE Database V5
Not known to be exploited · CVSS 9.2 Critical : upgrade to 5.2.8.3350 build 20251216 as a priority.
Data as of 25 Oct 2026, 19:02 UTC
- EPSS
- 0.7% chance of exploitation in 30 days – higher than 53% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.2.8.3350 build 20251216, h5.3.2.3354 build 20251225, h5.2.8.3350 build 20251216
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 11 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.
What to do
Upgrade QTS to 5.2.8.3350 build 20251216; QuTS hero to h5.3.2.3354 build 20251225 or h5.2.8.3350 build 20251216.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| QNAP Systems Inc.QTS | Affected
| Fixed in
|
| QNAP Systems Inc.QuTS hero | Affected
| Fixed in
|
AI-suggested
To mitigate CVE-2025-66277, organizations should immediately upgrade affected QNAP devices to the patched versions: QTS 5.2.8.3350 build 20251216 or later, QuTS hero h5.3.2.3354 build 20251225 or later, and QuTS hero h5.2.8.3350 build 20251216 or later. Beyond patching, network segmentation should be employed to isolate NAS devices from untrusted networks, limiting exposure to potential attackers. Implement strict firewall rules to restrict access to management interfaces and file services only to trusted IP addresses. Regularly audit NAS configurations and access logs to detect anomalous activities indicative of exploitation attempts. Disable unnecessary services and protocols on QNAP devices to reduce the attack surface. Employ strong authentication mechanisms and consider multi-factor authentication for administrative access, even though this vulnerability does not require authentication, to protect against other attack vectors. Maintain regular backups of critical data stored on NAS devices, ensuring backups are stored offline or in immutable formats to recover from potential data corruption or ransomware attacks.
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