CVE-2026-72809

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-72809", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "state": "PUBLISHED", "assignerShortName": "VulnCheck", "dateReserved": "2026-08-10T15:11:49.794Z", "datePublished": "2026-08-12T19:07:52.734Z", "dateUpdated": "2026-08-14T22:07:21.536Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-08-14T16:52:13.597Z"}, "datePublic": "2026-07-23T00:00:00.000Z", "title": "SiYuan before v3.7.4 Authentication Bypass via Localhost Trust", "descriptions": [{"lang": "en", "value": "SiYuan versions <= v3.7.2 (patched in v3.7.4) contain an authentication bypass vulnerability in the kernel's CheckAuth function, which grants the administrator role (RoleAdministrator) to any request whose RemoteAddr is loopback (127.0.0.1) for a specific set of endpoints (including /api/system/exit, getNetwork, getWorkspaceInfo, /assets/*, and /export/*). These localhost bypasses sit outside the access auth code gate, so they apply even when an access auth code is configured. Because the fixed-port reverse proxy forwards requests to the kernel over loopback without injecting an authentication token and does not configure trusted proxies, a request forwarded through this proxy reaches the kernel with RemoteAddr = 127.0.0.1. If the fixed-port proxy is bound to a network interface, this could allow a remote unauthenticated attacker to obtain admin access on the affected endpoints; however, per the advisory this remote forwarding behavior was established only by code inspection and was not reproduced end-to-end."}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "Authentication Bypass by Spoofing", "cweId": "CWE-290", "type": "CWE"}]}], "affected": [{"vendor": "siyuan-note", "product": "siyuan", "defaultStatus": "unaffected", "packageURL": "pkg:golang/github.com/siyuan-note/siyuan/kernel", "versions": [{"version": "0", "status": "affected", "versionType": "semver", "lessThan": "3.7.4"}, {"version": "3.7.4", "status": "unaffected", "versionType": "semver"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*", "versionEndExcluding": "3.7.4"}]}]}], "metrics": [{"format": "CVSS", "cvssV4_0": {"version": "4.0", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N", "attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "baseScore": 7.1, "baseSeverity": "HIGH"}}, {"format": "CVSS", "cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "availabilityImpact": "HIGH", "baseScore": 8, "baseSeverity": "HIGH"}}], "references": [{"url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3mp7-4rh5-jrv9", "tags": ["vendor-advisory"], "name": "GitHub Security Advisory (GHSA-3mp7-4rh5-jrv9)"}, {"name": "VulnCheck Advisory: SiYuan before v3.7.4 Authentication Bypass via Localhost Trust", "tags": ["third-party-advisory"], "url": "https://www.vulncheck.com/advisories/siyuan-before-authentication-bypass-via-localhost-trust"}], "credits": [{"lang": "en", "value": "Shirshakhtml", "type": "reporter"}], "x_generator": {"engine": "vulncheck-endgame"}}, "adp": [{"references": [{"url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3mp7-4rh5-jrv9", "tags": ["exploit"]}], "metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-08-14T22:06:55.491557Z", "id": "CVE-2026-72809", "options": [{"Exploitation": "poc"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-08-14T22:07:21.536Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-72809", "role": "CISA Coordinator", "options": [{"Exploitation": "poc"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-08-14T22:06:55.491557Z"}}}], "references": [{"url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3mp7-4rh5-jrv9", "tags": ["exploit"]}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-08-14T22:07:12.521Z"}}], "cna": {"title": "SiYuan before v3.7.4 Authentication Bypass via Localhost Trust", "credits": [{"lang": "en", "type": "reporter", "value": "Shirshakhtml"}], "metrics": [{"format": "CVSS", "cvssV4_0": {"version": "4.0", "baseScore": 7.1, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "LOW", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "HIGH"}}, {"format": "CVSS", "cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}}], "affected": [{"vendor": "siyuan-note", "product": "siyuan", "versions": [{"status": "affected", "version": "0", "lessThan": "3.7.4", "versionType": "semver"}, {"status": "unaffected", "version": "3.7.4", "versionType": "semver"}], "packageURL": "pkg:golang/github.com/siyuan-note/siyuan/kernel", "defaultStatus": "unaffected"}], "datePublic": "2026-07-23T00:00:00.000Z", "references": [{"url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3mp7-4rh5-jrv9", "name": "GitHub Security Advisory (GHSA-3mp7-4rh5-jrv9)", "tags": ["vendor-advisory"]}, {"url": "https://www.vulncheck.com/advisories/siyuan-before-authentication-bypass-via-localhost-trust", "name": "VulnCheck Advisory: SiYuan before v3.7.4 Authentication Bypass via Localhost Trust", "tags": ["third-party-advisory"]}], "x_generator": {"engine": "vulncheck-endgame"}, "descriptions": [{"lang": "en", "value": "SiYuan versions <= v3.7.2 (patched in v3.7.4) contain an authentication bypass vulnerability in the kernel's CheckAuth function, which grants the administrator role (RoleAdministrator) to any request whose RemoteAddr is loopback (127.0.0.1) for a specific set of endpoints (including /api/system/exit, getNetwork, getWorkspaceInfo, /assets/*, and /export/*). These localhost bypasses sit outside the access auth code gate, so they apply even when an access auth code is configured. Because the fixed-port reverse proxy forwards requests to the kernel over loopback without injecting an authentication token and does not configure trusted proxies, a request forwarded through this proxy reaches the kernel with RemoteAddr = 127.0.0.1. If the fixed-port proxy is bound to a network interface, this could allow a remote unauthenticated attacker to obtain admin access on the affected endpoints; however, per the advisory this remote forwarding behavior was established only by code inspection and was not reproduced end-to-end."}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-290", "description": "Authentication Bypass by Spoofing"}]}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "3.7.4"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-08-14T16:52:13.597Z"}}}, "cveMetadata": {"cveId": "CVE-2026-72809", "state": "PUBLISHED", "dateUpdated": "2026-08-14T22:07:21.536Z", "dateReserved": "2026-08-10T15:11:49.794Z", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "datePublished": "2026-08-12T19:07:52.734Z", "assignerShortName": "VulnCheck"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "packageURL": "pkg:golang/github.com/siyuan-note/siyuan/kernel", "product": "siyuan", "vendor": "siyuan-note", "versions": [{"lessThan": "3.7.4", "status": "affected", "version": "0", "versionType": "semver"}, {"status": "unaffected", "version": "3.7.4", "versionType": "semver"}]}], "source": "disclosure@vulncheck.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "SiYuan versions <= v3.7.2 (patched in v3.7.4) contain an authentication bypass vulnerability in the kernel's CheckAuth function, which grants the administrator role (RoleAdministrator) to any request whose RemoteAddr is loopback (127.0.0.1) for a specific set of endpoints (including /api/system/exit, getNetwork, getWorkspaceInfo, /assets/*, and /export/*). These localhost bypasses sit outside the access auth code gate, so they apply even when an access auth code is configured. Because the fixed-port reverse proxy forwards requests to the kernel over loopback without injecting an authentication token and does not configure trusted proxies, a request forwarded through this proxy reaches the kernel with RemoteAddr = 127.0.0.1. If the fixed-port proxy is bound to a network interface, this could allow a remote unauthenticated attacker to obtain admin access on the affected endpoints; however, per the advisory this remote forwarding behavior was established only by code inspection and was not reproduced end-to-end."}, {"lang": "es", "value": "Las versiones de SiYuan menor o igual a v3.7.2 (parcheadas en v3.7.4) contienen una vulnerabilidad de omisi\u00f3n de autenticaci\u00f3n en la funci\u00f3n CheckAuth del kernel, que otorga el rol de administrador (RoleAdministrator) a cualquier solicitud cuya RemoteAddr sea loopback (127.0.0.1) para un conjunto espec\u00edfico de endpoints (incluyendo /api/system/exit, getNetwork, getWorkspaceInfo, /assets/* y /export/*). Estas omisiones de localhost se encuentran fuera de la puerta de c\u00f3digo de autenticaci\u00f3n de acceso, por lo que se aplican incluso cuyo se configura un c\u00f3digo de autenticaci\u00f3n de acceso. Debido a que el proxy inverso de puerto fijo reenv\u00eda solicitudes al kernel a trav\u00e9s de loopback sin inyectar un token de autenticaci\u00f3n y no configura proxies de confianza, una solicitud reenviada a trav\u00e9s de este proxy llega al kernel con RemoteAddr = 127.0.0.1. Si el proxy de puerto fijo est\u00e1 vinculado a una interfaz de red, esto podr\u00eda permitir a un atacante remoto no autenticado obtener acceso de administrador en los endpoints afectados; sin embargo, seg\u00fan el aviso, este comportamiento de reenv\u00edo remoto se estableci\u00f3 solo mediante inspecci\u00f3n de c\u00f3digo y no se reprodujo de extremo a extremo."}], "id": "CVE-2026-72809", "lastModified": "2026-10-23T22:10:00.160", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 8.0, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H", "version": "3.1"}, "exploitabilityScore": 2.5, "impactScore": 5.5, "source": "disclosure@vulncheck.com", "type": "Secondary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "LOCAL", "availabilityRequirement": "NOT_DEFINED", "baseScore": 7.1, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "LOW", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "disclosure@vulncheck.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-72809", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-08-14T22:06:55.491557Z", "version": "2.0.3"}}]}, "published": "2026-08-12T20:17:53.110", "references": [{"source": "disclosure@vulncheck.com", "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3mp7-4rh5-jrv9"}, {"source": "disclosure@vulncheck.com", "url": "https://www.vulncheck.com/advisories/siyuan-before-authentication-bypass-via-localhost-trust"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3mp7-4rh5-jrv9"}], "sourceIdentifier": "disclosure@vulncheck.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-290"}], "source": "disclosure@vulncheck.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,3.7.4)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "3.7.4"}}], "enrichment": {"confidence": 84.0, "confidence_source": "matching", "scores": [{"score": 84.0, "source": "matching"}]}, "original": {"product": "siyuan", "source": "cna", "vendor": "siyuan-note"}, "product": "siyuan", "vendor": "siyuan"}], "created": "2026-08-12T23:00:05.328606+00:00", "updated": "2026-08-13T10:15:07.215826+00:00", "vendors": ["siyuan", "siyuan$PRODUCT$siyuan"]}