VDB-428324 · CVE-2025-62839 · GCVE-0-2025-62839

QNAP Hybrid Backup Sync/Hybrid Backup Sync prior 26.4.0.521/26.4.1.563 hard-coded key

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.
7.0	$0-$5k	1.93

Summaryinfo

A vulnerability categorized as critical has been discovered in QNAP Hybrid Backup Sync and Hybrid Backup Sync. The affected element is an unknown function. Such manipulation leads to hard-coded key. This vulnerability is traded as CVE-2025-62839. The attack may be launched remotely. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in QNAP Hybrid Backup Sync and Hybrid Backup Sync and classified as critical. Affected by this issue is an unknown functionality. The manipulation with an unknown input leads to a hard-coded key vulnerability. Using CWE to declare the problem leads to CWE-321. The use of a hard-coded cryptographic key significantly increases the possibility that encrypted data may be recovered. Impacted is confidentiality, integrity, and availability. CVE summarizes:

An use of hard-coded cryptographic key vulnerability has been reported to affect HBS 3 Hybrid Backup Sync and Hybrid Backup Sync. If exploited, the vulnerability could allow remote attackers to compromise the security of the system. We have already fixed the vulnerability in the following version: HBS 3 Hybrid Backup Sync 26.4.0.521 and later Hybrid Backup Sync 26.4.0.521 and later Hybrid Backup Sync 26.4.1.563 and later

The advisory is shared for download at qnap.com. This vulnerability is handled as CVE-2025-62839 since 10/24/2025. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1600.001.

Upgrading to version 26.4.0.521 or 26.4.1.563 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Backup Software

Vendor

QNAP

Name

License

commercial

Website

Vendor: https://www.qnap.com/

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: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

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: Hard-coded key
CWE: CWE-321 / CWE-320
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
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: 🔒

Upgrade: Hybrid Backup Sync/Hybrid Backup Sync 26.4.0.521/26.4.1.563

Timelineinfo

10/24/2025 CVE reserved
10/29/2026 +370 days Advisory disclosed
10/29/2026 +0 days VulDB entry created
10/29/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: qnap.com

Advisory: qnap.com
Status: Confirmed

CNA: qnap
CVE: CVE-2025-62839 (🔒)

GCVE (CVE): GCVE-0-2025-62839
GCVE (VulDB): GCVE-100-428324

Entryinfo

Created: 10/29/2026 09:05
Changes: 10/29/2026 09:05 (65)
Complete: 🔍
Cache ID: 216::103