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Qts CVE-2025-66277

CRITICAL
Improper Link Resolution Before File Access (CWE-59)
2026-02-11 security@qnapsecurity.com.tw
9.8
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V5 - File Handling Symlink resolution safety
Impact

CVSS 9.8. QNAP NAS devices store business data, backups, and personal files.

Exploit ScenarioDerived

Remote attacker exploits symlink following to read/write files on the NAS beyond intended access scope.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.
No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Symlink following vulnerability in multiple QNAP NAS operating system versions allows remote attackers to exploit link resolution for unauthorized access.

Earlier versions of this analysis (1)
v1 Mar 12, 2026 - 22:02 CVSS 9.8

Symlink following in QNAP NAS operating system.

RemediationAI

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Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

CWE-59 link following vulnerability. QNAP NAS follows symlinks allowing access to files outside intended scope.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

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

Executive ViewAI

Why It Matters

A critical vulnerability (CVE-2025-66277, CVSS 9.8) in QNAP operating systems allows remote attackers to traverse file systems and access unauthorized data. This poses an immediate risk to any organization using affected QNAP devices, potentially exposing sensitive business data, configurations, and system files without requiring authentication.

Business Impact: Severe
Compensating Controls

Until vendor patch is available: (1) Implement network-level access controls restricting QNAP device connectivity to authorized users/systems only; (2) Deploy WAF or reverse proxy rules to block suspicious path traversal patterns (../, encoded variants); (3) Disable unnecessary QNAP services and management interfaces; (4) Segment QNAP devices on isolated VLANs; (5) Enable comprehensive audit logging and implement SIEM alerting for file access anomalies; (6) Consider temporary service degradation by taking non-critical QNAP devices offline until patch becomes available.

Threat Intelligence Overview

EPSS Score
0.1%
Top 75% exploitable
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.1%
Patch available No
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Out-of-Cycle
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
Very High

Priority Score

49
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Affected Products (CPE)CVE.org

cpe:2.3:o:qnap:qts:5.2.0.2737:build_20240417:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.0.2744:build_20240424:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.0.2782:build_20240601:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.0.2802:build_20240620:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.0.2823:build_20240711:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.0.2851:build_20240808:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.0.2860:build_20240817:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.1.2930:build_20241025:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.2.2950:build_20241114:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.3.3006:build_20250108:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.4.3070:build_20250312:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.4.3079:build_20250321:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.4.3092:build_20250403:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.5.3145:build_20250526:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.6.3195:build_20250715:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.6.3229:build_20250818:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.7.3256:build_20250913:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.7.3297:build_20251024:*:*:*:*:*:*
cpe:2.3:o:qnap:qts:5.2.8.3332:build_20251128:*:*:*:*:*:*
cpe:2.3:o:qnap:quts_hero:h5.2.0.2737:build_20240417:*:*:*:*:*:*
+ 17 more

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