CVE-2026-72809 (GCVE-0-2026-72809)

Vulnerability from cvelistv5 – Published: 2026-08-12 19:07 – Updated: 2026-08-14 22:07
VLAI
Title
SiYuan before v3.7.4 Authentication Bypass via Localhost Trust
Summary
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.
Severity
7.1 (High)
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
8 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-14 22:06 UTC
CWE
  • CWE-290 - Authentication Bypass by Spoofing
Assigner
VulnCheck CNA under the mitre root
CNA scorecard B 84/100 over 7140 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
siyuan-note siyuan Affected: 0 , < 3.7.4 (semver)
Unaffected: 3.7.4 (semver)
    cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*
Create a notification for this product.
Date Public
2026-07-23 00:00
Credits
Shirshakhtml
Show details on NVD website
To clipboard 

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