CVE-2026-72809

What it is

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.

At a glance

Exploitability

Can be exploited locally on the machine without logging in. High risk of data exposure, service disruption.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-08-12 20:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-23 22:10 UTC Last updatedMost recent change to the record

Details

Published

2026-08-12 20:17 UTC

Last modified

2026-10-23 22:10 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-290

Record status

Deferred

Attack profile CVSS 4.0 · 7.1

Attack vector

Local

Complexity

Low

Attack requirements

None

Privileges needed

None

User interaction

None

Confidentiality

High

Integrity

Low

Availability

High