{"id":"CVE-2026-72809","revision":"f067be404ac445f182f3a53221e99a5b","records":[{"revision":"f067be404ac445f182f3a53221e99a5b","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-72809","aliases":[],"title":"SiYuan before v3.7.4 Authentication Bypass via Localhost Trust","description":"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.","state":0,"publishedAt":"2026-08-12T19:07:52.734+00:00","modifiedAt":"2026-08-14T22:07:21.536+00:00","affected":[{"ecosystem":"Vendor product","name":"siyuan","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"siyuan-note\",\n                    \"product\": \"siyuan\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"packageURL\": \"pkg:golang/github.com/siyuan-note/siyuan/kernel\",\n                    \"versions\": [\n                        {\n                            \"version\": \"0\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\",\n                            \"lessThan\": \"3.7.4\"\n                        },\n                        {\n                            \"version\": \"3.7.4\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"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","score":7.1,"severity":"HIGH"},{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H","score":8,"severity":"HIGH"}],"references":["https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3mp7-4rh5-jrv9","https://www.vulncheck.com/advisories/siyuan-before-authentication-bypass-via-localhost-trust"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72809","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-72809","identifiers":["CVE-2026-72809"]},"retained":false,"historicalAffected":[]}],"coverage":[]}