CVE-2026-66012

CVE

Threat entity extracted from intelligence sources

Frequency

4

occurrences

First Seen

July 25, 2026

Last Seen

July 26, 2026

Exploited in Wild

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Ransomware Use

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Public Exploits

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Attack Vector

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Vulnerability Overview

Exploitation Activity

Exploitation Intelligence

Critical Authorization Vulnerability in SiYuan (CVE-2026-66012)78.0

A critical missing authorization vulnerability (CVE-2026-66012) has been identified in SiYuan versions prior to 3.7.2, allowing remote unauthenticated attackers to bypass authentication on the POST /mcp kernel endpoint. This vulnerability exposes 31 MCP tools, including file management capabilities,...

Public Exploits

Checking GitHub for proof-of-concept code…

Related Clusters (1)

Critical Authorization Vulnerability in SiYuan (CVE-2026-66012)

Jul 26·2 sources

Related Articles (4)

MCP as a Backdoor: CVE-2026-66012 — How a Missing Authorization Check in SiYuan's MCP Endpoint Turns Anonymous Readers into Administrators HB - Tailored Software Solutions / 1h The vulnerability, disclosed via GitHub Security Advisory GHSA-cvhv-7xhj-xjp8 on July 13, 2026, chains three independent defects in SiYuan’s kernel into an unauthenticated, network-reachable path to arbitrary workspace file read/write/delete, plaintext credential exfiltration, and remote code execution via plugin planting

www.hunt-benito.com·Jul 26

CVE-2026-66012 INCIBE-CERT - Vulnerabilities RSS / 19h 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. This exposes 31 MCP tools, including a file tool with list/read/write/delete/rename/copy actions across the entire workspace.

www.incibe.es·Jul 26

CVE-2026-66012: SiYuan before v3.7.2 Unauthenticated Administrator Takeover via MCP [CRITICAL] CVSS 10.0 Exploit Intelligence — Recent CVEs / 22h 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 ac

exploit-intel.com·Jul 26

CVE-2026-66012 - Exploits & Severity

Related Entities

Data Breach Zero-day Exploit SiYuan CWE-200 - Exposure of Sensitive Information CWE-287 - Improper Authentication CWE-269 - Improper Privilege Management T1190 - Exploit Public-Facing Application T1068 - Exploitation for Privilege Escalation T1071 - Application Layer Protocol T1134 - Access Token Manipulation T1552.001 - Credentials In Files Go