QNAP Systems QTS/QuTS hero link following

HistoryDiffrelatejsonxmlCTI

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
9.6	$0-$5k	0.00

Summaryinfo

A vulnerability has been found in QNAP Systems QTS and QuTS hero and classified as critical. This issue affects some unknown processing. This manipulation causes link following. This vulnerability is handled as CVE-2025-66277. The attack can be initiated remotely. There is not any exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in QNAP Systems QTS and QuTS hero (the affected version unknown). It has been declared as very critical. Affected by this vulnerability is an unknown part. The manipulation with an unknown input leads to a link following vulnerability. The CWE definition for the vulnerability is CWE-59. The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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

The weakness was released by coral as qsa-26-05. The advisory is shared at qnap.com. This vulnerability is known as CVE-2025-66277 since 11/26/2025. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 02/12/2026).

Upgrading eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

QNAP Systems

Name

License

commercial

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 9.8
VulDB Meta Temp Score: 9.6

VulDB Base Score: 9.8
VulDB Temp Score: 9.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Link following
CWE: CWE-59
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Timelineinfo

11/26/2025 CVE reserved
02/11/2026 +77 days Advisory disclosed
02/11/2026 +0 days VulDB entry created
02/12/2026 +1 days VulDB entry last update

Sourcesinfo

Advisory: qsa-26-05
Researcher: coral
Status: Confirmed

CVE: CVE-2025-66277 (🔒)
GCVE (CVE): GCVE-0-2025-66277
GCVE (VulDB): GCVE-100-345481

Entryinfo

Created: 02/11/2026 14:43
Updated: 02/12/2026 22:50
Changes: 02/11/2026 14:43 (66), 02/12/2026 22:50 (10)
Complete: 🔍
Cache ID: 216::103