CVE-2026-66012Public exploitNetwork attack vector

Unauthenticated administrator takeover via missing MCP authorization

Published Jul 25, 2026 · Updated Jul 25, 2026

Missing authorization in SiYuan before 3.7.2 allows remote attackers to take over an administrator account through the POST /mcp endpoint. The route applies only model.CheckAuth, while the anonymous Publish proxy supplies a RoleReader JWT that can invoke workspace-wide MCP file operations without an administrator or read-only check. Anonymous Publish mode must be enabled; exposed attackers can read stored credentials, alter or delete workspace files, and plant a plugin that executes on the next desktop launch.

CVSS severity10.0
Critical
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authorization in SiYuan before 3.7.2 allows remote attackers to take over an administrator account through the POST /mcp endpoint. The route applies only model.CheckAuth, while the anonymous Publish proxy supplies a RoleReader JWT that can invoke workspace-wide MCP file operations without an administrator or read-only check. Anonymous Publish mode must be enabled; exposed attackers can read stored credentials, alter or delete workspace files, and plant a plugin that executes on the next desktop launch.

The record

CVE
CVE-2026-66012
Published
Jul 25, 2026
Updated
Jul 25, 2026
Vendor
SiYuan Note
Product
SiYuan
Classifications
CWE-862, T1552.001, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.7.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SiYuan Note · SiYuanversion=0 <3.7.2

Published CVSS scores

10.0VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
10.0VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-862Missing Authorization
T1552.001Credentials In Files
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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