{"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": "2026-08-12T19:07:52.734Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-08-12T19:07:52.734Z"}, "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"}]}], "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"}}}}

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{"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."}], "id": "CVE-2026-72809", "lastModified": "2026-08-12T20:17:53.110", "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": "Primary"}], "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"}]}, "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"}], "sourceIdentifier": "disclosure@vulncheck.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-290"}], "source": "disclosure@vulncheck.com", "type": "Primary"}]}

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