Synology SSL VPN Client up to 1.4.5-0683 Loopback Interface file access

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.
5.3	$0-$5k	0.00

Summaryinfo

A vulnerability labeled as problematic has been found in Synology SSL VPN Client up to 1.4.5-0683. The impacted element is an unknown function of the component Loopback Interface. The manipulation results in file access. This vulnerability is cataloged as CVE-2021-47960. The attack may be launched remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as problematic has been found in Synology SSL VPN Client up to 1.4.5-0683. Affected is an unknown part of the component Loopback Interface. The manipulation with an unknown input leads to a file access vulnerability. CWE is classifying the issue as CWE-552. The product makes files or directories accessible to unauthorized actors, even though they should not be. This is going to have an impact on confidentiality. CVE summarizes:

A files or directories accessible to external parties vulnerability in Synology SSL VPN Client before 1.4.5-0684 allows remote attackers to access files within the installation directory via a local HTTP server bound to the loopback interface. By leveraging user interaction with a crafted web page, attackers may retrieve sensitive files such as configuration files, certificates, and logs, leading to information disclosure.

The advisory is available at synology.com. This vulnerability is traded as CVE-2021-47960 since 04/10/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1083 by the MITRE ATT&CK project.

Upgrading to version 1.4.5-0684 eliminates this vulnerability.

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Productinfo

Type

Network Encryption Software

Vendor

Synology

Name

SSL VPN Client

Version

1.4.5-0683

License

commercial

Website

Vendor: https://www.synology.com/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.4
VulDB Meta Temp Score: 5.3

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.5
CNA Vector (synology): 🔒

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: File access
CWE: CWE-552 / CWE-425
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: 🔒

Upgrade: SSL VPN Client 1.4.5-0684

Timelineinfo

04/10/2026 Advisory disclosed
04/10/2026 +0 days CVE reserved
04/10/2026 +0 days VulDB entry created
04/10/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: synology.com

Advisory: SA_26_05
Status: Confirmed

CVE: CVE-2021-47960 (🔒)
GCVE (CVE): GCVE-0-2021-47960
GCVE (VulDB): GCVE-100-356814

Entryinfo

Created: 04/10/2026 15:49
Changes: 04/10/2026 15:49 (66)
Complete: 🔍
Cache ID: 216::103