CVE-2026-66012

CRITICALPre-NVD 10.010.0—
EchelonGraph scoreHIGH confidence

Score 10.0 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-25. a secondary CVSS source baseline 10.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
10.0EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 10.0Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
10.0
EG Score
10.0(high)
EG Risk
50(Track)
EG Risk 50/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity100% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
36%
KEV
Not listed

Published

July 25, 2026

Last Modified

July 25, 2026

Advisory Details (3)

Auto-updated Jul 25, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github.
generic

SiYuan before v3.7.2 Unauthenticated Administrator Takeover via MCP | Advisories | VulnCheck

https://www.vulncheck.com/advisories/siyuan-before-unauthenticated-administrator-takeover-via-mcp
github Patch Available🟡 PoC Available

Unauthenticated Administrator takeover exfiltrated via the MCP · Advisory · siyuan-note/siyuan · GitHub

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-cvhv-7xhj-xjp8
github_commit

commit c72ca4cd0901 (siyuan-note/siyuan)

Fix landed in siyuan-note/siyuan commit c72ca4cd0901 — awaiting tagged release

https://github.com/siyuan-note/siyuan/commit/c72ca4cd09019e5f64afdee8f8c6ec5ef34858db

Vendor Advisories for CVE-2026-66012(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 13× in last 7d / 13× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-27 01:36 UTCGHSA enrichment
  2. 2026-07-26 21:37 UTCGHSA enrichment
  3. 2026-07-26 17:39 UTCEG score recompute
  4. 2026-07-26 17:39 UTCGHSA enrichment
  5. 2026-07-26 14:54 UTCEPSS rescore
  6. 2026-07-26 14:54 UTCEPSS rescore
  7. 2026-07-26 13:41 UTCEG score recompute
  8. 2026-07-26 13:41 UTCGHSA enrichment
  9. 2026-07-26 09:43 UTCGHSA enrichment
  10. 2026-07-26 02:45 UTCEG score recompute
  11. 2026-07-26 02:45 UTCGHSA enrichment
  12. 2026-07-25 11:02 UTCEG score recompute
  13. 2026-07-25 11:01 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-66012?
CVE-2026-66012 is a critical vulnerability published on July 25, 2026. 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…
When was CVE-2026-66012 disclosed?
CVE-2026-66012 was first published in the National Vulnerability Database on July 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66012 actively exploited?
CVE-2026-66012 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 64.2% of all scored CVEs.
What is the CVSS score of CVE-2026-66012?
CVE-2026-66012 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2026-66012?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66012, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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