CVE-2021-47961

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2021-47961", "assignerOrgId": "db201096-a0cc-46c7-9a55-61d9e221bf01", "state": "PUBLISHED", "assignerShortName": "synology", "dateReserved": "2026-04-10T06:29:38.695Z", "datePublished": "2026-04-10T09:22:37.522Z", "dateUpdated": "2026-04-10T12:42:56.656Z"}, "containers": {"cna": {"problemTypes": [{"descriptions": [{"lang": "en", "description": "Plaintext Storage of a Password", "cweId": "CWE-256", "type": "CWE"}]}], "affected": [{"vendor": "Synology", "product": "Synology SSL VPN Client", "versions": [{"version": "*", "status": "affected", "lessThan": "1.4.5-0684", "versionType": "semver"}], "defaultStatus": "affected"}], "descriptions": [{"lang": "en", "value": "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."}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV3_1": {"baseScore": 8.1, "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE", "version": "3.1"}}], "references": [{"url": "https://www.synology.com/en-global/security/advisory/Synology_SA_26_05", "name": "Synology-SA-26:05 Synology SSL VPN Client", "tags": ["vendor-advisory"]}], "credits": [{"lang": "en", "value": "Laurent Sibilla (https://www.linkedin.com/in/lsibilla/)", "type": "finder"}], "providerMetadata": {"orgId": "db201096-a0cc-46c7-9a55-61d9e221bf01", "shortName": "synology", "dateUpdated": "2026-04-10T09:22:37.522Z"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-04-10T12:42:50.035627Z", "id": "CVE-2021-47961", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-04-10T12:42:56.656Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2021-47961", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-04-10T12:42:50.035627Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-04-10T12:42:53.753Z"}}], "cna": {"credits": [{"lang": "en", "type": "finder", "value": "Laurent Sibilla (https://www.linkedin.com/in/lsibilla/)"}], "metrics": [{"format": "CVSS", "cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 8.1, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N", "integrityImpact": "HIGH", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "affected": [{"vendor": "Synology", "product": "Synology SSL VPN Client", "versions": [{"status": "affected", "version": "*", "lessThan": "1.4.5-0684", "versionType": "semver"}], "defaultStatus": "affected"}], "references": [{"url": "https://www.synology.com/en-global/security/advisory/Synology_SA_26_05", "name": "Synology-SA-26:05 Synology SSL VPN Client", "tags": ["vendor-advisory"]}], "descriptions": [{"lang": "en", "value": "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."}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-256", "description": "Plaintext Storage of a Password"}]}], "providerMetadata": {"orgId": "db201096-a0cc-46c7-9a55-61d9e221bf01", "shortName": "synology", "dateUpdated": "2026-04-10T09:22:37.522Z"}}}, "cveMetadata": {"cveId": "CVE-2021-47961", "state": "PUBLISHED", "dateUpdated": "2026-04-10T12:42:56.656Z", "dateReserved": "2026-04-10T06:29:38.695Z", "assignerOrgId": "db201096-a0cc-46c7-9a55-61d9e221bf01", "datePublished": "2026-04-10T09:22:37.522Z", "assignerShortName": "synology"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "affected", "product": "Synology SSL VPN Client", "vendor": "Synology", "versions": [{"lessThan": "1.4.5-0684", "status": "affected", "version": "*", "versionType": "semver"}]}], "source": "security@synology.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:synology:ssl_vpn_client:*:*:*:*:*:*:*:*", "matchCriteriaId": "3B17E85E-878A-4B10-A4B2-4359305FFC08", "versionEndExcluding": "1.4.5-0684", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2021-47961", "lastModified": "2026-06-17T04:18:50.197", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.2, "source": "security@synology.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2021-47961", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-04-10T12:42:50.035627Z", "version": "2.0.3"}}]}, "published": "2026-04-10T10:16:03.913", "references": [{"source": "security@synology.com", "tags": ["Vendor Advisory"], "url": "https://www.synology.com/en-global/security/advisory/Synology_SA_26_05"}], "sourceIdentifier": "security@synology.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-256"}], "source": "security@synology.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,1.4.5-0684)"}}], "enrichment": {"confidence": 84.0, "confidence_source": "matching", "scores": [{"score": 84.0, "source": "matching"}]}, "original": {"product": "Synology SSL VPN Client", "source": "cna", "vendor": "Synology"}, "product": "ssl_vpn_client", "vendor": "synology"}], "analysis": {"en": {"generated_at": "2026-04-10T10:50:27.481546+00:00", "value": {"mitigation_remediation": ["Upgrade Synology SSL VPN Client to version 1.4.5\u20110684 or later"], "summary": {"action": "Patch Immediately", "impact": "Unauthorized VPN configuration and potential traffic interception"}, "threat_synthesis": {"affected_systems": "Synology SSL VPN Client, all releases earlier than 1.4.5\u20110684.", "description_and_impact": "An insecure storage mechanism in Synology SSL VPN Client versions before 1.4.5\u20110684 records the user\u2019s PIN in plain text. This weakness allows an attacker to read or modify the PIN, which can in turn enable unauthorized configuration of the VPN or compromise the integrity of subsequent VPN traffic. The flaw is a password storage vulnerability, identified as CWE\u2011256.", "risk_and_exploitability": "The CVSS score of 8.1 signals high severity. No EPSS data or KEV listing indicates that widespread exploitation has not yet been observed, although the vulnerability remains theoretically exploitable. Achieving the attack likely requires the attacker to gain access to the client on the user\u2019s machine, such as through malicious software or local privilege escalation, to read or alter the stored PIN. Once the PIN is compromised, an attacker can configure the VPN or trick the user into accepting changes, which may allow interception or tampering of VPN traffic."}}}}, "created": "2026-04-13T12:44:57.808915+00:00", "title": "Plaintext Password Storage in Synology SSL VPN Client Enabling Unauthorized VPN Configuration", "updated": "2026-04-13T13:06:11.086868+00:00", "vendors": ["synology", "synology$PRODUCT$ssl_vpn_client"]}