CVE-2025-66277Network attack vector

Unauthenticated file-system traversal via link following

Published Feb 11, 2026 · Updated Feb 11, 2026

Link following in QNAP QTS 5.2.x and QuTS hero h5.2.x and h5.3.x allows remote attackers to traverse the file system. The vendor has not disclosed the affected component or how it resolves attacker-controlled links into paths outside intended locations. No authentication is required, but exploitation depends on an unspecified attack condition, and the exact files or operations exposed remain undisclosed.

CVSS severity9.2
Critical
EPSS probability0.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Link following in QNAP QTS 5.2.x and QuTS hero h5.2.x and h5.3.x allows remote attackers to traverse the file system. The vendor has not disclosed the affected component or how it resolves attacker-controlled links into paths outside intended locations. No authentication is required, but exploitation depends on an unspecified attack condition, and the exact files or operations exposed remain undisclosed.

The record

CVE
CVE-2025-66277
Published
Feb 11, 2026
Updated
Feb 11, 2026
Vendor
Linn Products Limited
Product
QuTS hero
Classifications
CWE-59, CAPEC-132
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=h5.2.x <h5.2.8.3350 build 20251216
  2. Affected versionversion=h5.3.x <h5.3.2.3354 build 20251225

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Linn Products Limited · QuTS heroversion=h5.2.x <h5.2.8.3350 build 20251216; version=h5.3.x <h5.3.2.3354 build 20251225
Linn Products Limited · QTSversion=5.2.x <5.2.8.3350 build 20251216

Published CVSS scores

9.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.2QNAP Systems Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-59Improper Link Resolution Before File Access ('Link Following')
CAPEC-132Symlink Attack

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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