CVE-2021-47961 | Synology SSL VPN Client up to 1.4.5-0683 VPN Configuration credentials storage (SA_26_05)

VDB-356809 · CVE-2021-47961 · SA_26_05 SYNOLOGY SSL VPN CLIENT UP TO 1.4.5-0683 VPN CONFIGURATION CREDENTIALS STORAGE HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 6.1 $0-$5k 1.54+ Summaryinfo A vulnerability was found in Synology SSL VPN Client up to 1.4.5-0683. It has been classified as problematic. This affects an unknown part of the component VPN Configuration Handler. This manipulation causes credentials storage. The identification of this vulnerability is CVE-2021-47961. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is recommended. Detailsinfo A vulnerability has been found in Synology SSL VPN Client up to 1.4.5-0683 and classified as problematic. Affected by this vulnerability is an unknown code block of the component VPN Configuration Handler. The manipulation with an unknown input leads to a credentials storage vulnerability. The CWE definition for the vulnerability is CWE-256. Storing a password in plaintext may result in a system compromise. As an impact it is known to affect confidentiality. The summary by CVE is: A plaintext storage of a password vulnerability in Synology SSL VPN Client before 1.4.5-0684 allows remote attackers to access or influence the user's PIN code due to insecure storage. This may lead to unauthorized VPN configuration and potential interception of subsequent VPN traffic when combined with user interaction. The advisory is shared at synology.com. This vulnerability is known as CVE-2021-47961 since 04/10/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1552 for this issue. Upgrading to version 1.4.5-0684 eliminates this vulnerability. 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: 6.2 VulDB Meta Temp Score: 6.1 VulDB Base Score: 4.3 VulDB Temp Score: 4.1 VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA Base Score: 8.1 CNA Vector (synology): 🔒 CVSSv2info 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: Credentials storage CWE: CWE-256 / CWE-255 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: 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-2021-47961 (🔒) GCVE (CVE): GCVE-0-2021-47961 GCVE (VulDB): GCVE-100-356809 Entryinfo Created: 04/10/2026 15:49 Changes: 04/10/2026 15:49 (66) Complete: 🔍 Cache ID: 99:415:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸