23 Oct 2026 15:48:27 UTC
SiYuan before v3.7.2 Unauthenticated Administrator Takeover via MCP
cve-program · CVE-2026-66012 · Published
CVE-2026-66012
SiYuan before v3.7.2 Unauthenticated Administrator Takeover via MCP
CVSS 4.0 10.0 CRITICALCVSS 3.1 10.0 CRITICALCheck source for fixed versionsKEV status unknown
cve-program · CVE-2026-66012
PublishedSiYuan before v3.7.2 contains a missing authorization vulnerability in the POST /mcp kernel endpoint, which is gated only by a general auth check (model.CheckAuth) with no admin-role or read-only enforcement. This exposes 31 MCP tools, including a file tool with list/read/write/delete/rename/copy actions across the entire workspace. When the Publish server is enabled in anonymous mode (Conf.Publish.Enable=true and Conf.Publish.Auth.Enable=false), the Publish reverse proxy attaches an anonymous RoleReader JWT to proxied requests, allowing a remote unauthenticated attacker to reach /mcp. The attacker can read conf/conf.json to extract accessAuthCode, api.token, and cookieKey in plaintext, write arbitrary files in the workspace, and plant a plugin into data/plugins/ that executes with nodeIntegration:true and no contextIsolation on the next desktop launch, leading to administrator takeover.
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