Vulnerability 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.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3mp7-4rh5-jrv9
- https://www.vulncheck.com/advisories/siyuan-before-authentication-bypass-via-loc
- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3mp7-4rh5-jrv9
FAQ
What is CVE-2026-72809?
CVE-2026-72809 is a vulnerability with a CVSS score of 8.0 (HIGH). 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 ...
How severe is CVE-2026-72809?
CVE-2026-72809 has been rated HIGH with a CVSS base score of 8.0/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-72809?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.