{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "0"
                  },
                  {
                    "last_affected": "3.7.2"
                  }
                ],
                "source": "DESCRIPTION"
              }
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "726dae1d518927f70ea609bc146288b9aa95e366"
            }
          ],
          "repo": "https://github.com/siyuan-note/siyuan",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-3mp7-4rh5-jrv9"
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-290"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72809.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "range": [
              {
                "fixed": "3.7.4"
              }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StandardRange"
          }
        ]
      },
      {
        "extracted_events": [
          {
            "range": [
              {
                "fixed": "3.7.4"
              }
            ],
            "source": "CPE_FIELD",
            "strategy": "CPEApplicability"
          }
        ]
      },
      {
        "extracted_events": [
          {
            "range": [
              {
                "fixed": "3.7.4"
              }
            ],
            "source": "DESCRIPTION"
          }
        ]
      }
    ]
  },
  "details": "SiYuan versions \u003c= 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",
  "modified": "2026-10-21T02:30:20.909833682Z",
  "published": "2026-08-12T19:07:52.734Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72809.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3mp7-4rh5-jrv9"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72809"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/siyuan-before-authentication-bypass-via-localhost-trust"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "SiYuan before v3.7.4 Authentication Bypass via Localhost Trust"
}