{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/synology/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[{"cvss":8.1,"id":"CVE-2021-47961"}],"_cs_exploited":false,"_cs_products":[],"_cs_severities":["high"],"_cs_tags":["plaintext-password","vpn","synology"],"_cs_type":"advisory","_cs_vendors":[],"content_html":"\u003cp\u003eCVE-2021-47961 describes a vulnerability in Synology SSL VPN Client versions prior to 1.4.5-0684. The client software stores user passwords in plaintext, creating a security risk. An attacker with access to the system or the client\u0026rsquo;s configuration files could potentially retrieve these passwords and use them to manipulate the VPN configuration. Successful exploitation of this vulnerability can lead to unauthorized access to the VPN, as well as the potential interception and monitoring of VPN traffic. This is particularly concerning for organizations relying on secure VPN connections for remote access and data transmission. This vulnerability was disclosed on April 10, 2026.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAttacker gains unauthorized access to the targeted system, either through physical access or remote access methods.\u003c/li\u003e\n\u003cli\u003eAttacker locates the Synology SSL VPN Client configuration file(s) on the compromised system.\u003c/li\u003e\n\u003cli\u003eAttacker opens the configuration file and retrieves the plaintext password stored within.\u003c/li\u003e\n\u003cli\u003eAttacker uses the retrieved password to access or modify the user\u0026rsquo;s PIN code within the VPN client.\u003c/li\u003e\n\u003cli\u003eAttacker reconfigures the VPN client settings, potentially redirecting traffic through a malicious server.\u003c/li\u003e\n\u003cli\u003eUser connects to the VPN using the modified configuration.\u003c/li\u003e\n\u003cli\u003eAll VPN traffic from the user\u0026rsquo;s machine is now routed through the attacker\u0026rsquo;s server.\u003c/li\u003e\n\u003cli\u003eAttacker intercepts and monitors the user\u0026rsquo;s VPN traffic, gaining access to sensitive data.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of CVE-2021-47961 allows attackers to gain unauthorized access to sensitive data transmitted through the VPN connection. The number of victims is dependent on the number of deployments using the vulnerable Synology SSL VPN client version prior to 1.4.5-0684. Sectors utilizing Synology SSL VPN clients for remote access are particularly at risk. A successful attack can lead to data breaches, intellectual property theft, and potential compromise of internal systems.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpgrade Synology SSL VPN Client to version 1.4.5-0684 or later to patch CVE-2021-47961.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u0026ldquo;Detect Synology VPN Client Configuration File Access\u0026rdquo; to detect unauthorized access to configuration files.\u003c/li\u003e\n\u003cli\u003eMonitor network traffic for unusual VPN connection patterns indicative of traffic redirection, using existing network monitoring tools.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-04-10T10:16:03Z","date_published":"2026-04-10T10:16:03Z","id":"/briefs/2026-04-synology-vpn-vuln/","summary":"Synology SSL VPN Client before 1.4.5-0684 stores passwords in plaintext, allowing remote attackers to potentially access or manipulate user PIN codes, leading to unauthorized VPN configuration and traffic interception.","title":"Synology SSL VPN Client Plaintext Password Storage Vulnerability (CVE-2021-47961)","url":"https://feed.craftedsignal.io/briefs/2026-04-synology-vpn-vuln/"}],"language":"en","title":"CraftedSignal Threat Feed — Synology","version":"https://jsonfeed.org/version/1.1"}