CVE-2026-66012

CVSS 10.0 · CRITICAL
EPSS p36
Lower risk — in the top 64% least-likely-to-be-exploited CVEs.
No patch reference
No patch/mitigation in references

Published 7/25/2026 · updated 7/25/2026 · CWE-862

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Summary

SiYuan 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.

CVSS 10.0CRITICAL

10.0 / 10
  • AV: Network
  • AC: Low complexity
  • PR: No privileges
  • UI: No user interaction
  • S: Scope changed
  • C: Confidentiality: High
  • I: Integrity: High
  • A: Availability: High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS exploitation probability

0.4%

Percentile p36 Lower risk — in the top 64% least-likely-to-be-exploited CVEs.

Timeline

  1. Jul 25, 2026 · Disclosed / published in NVD

Intel sources

Which upstream feeds returned data for this CVE, and when they were last fetched.

  • NVD· 7 days ago
  • CVE.org· 7 days ago
  • FIRST EPSS· 7 days ago
  • CISA KEV· no data
  • OSV· 7 days ago

References

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