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 • July 26, 2026

Puntuación base: 10.00 CRÍTICA Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Vector de acceso (AV): A través de red Complejidad de acceso (AC): Bajo Attack Requirements (AT): Ninguno Privilegios Requeridos (PR): Ninguno Interacción del usuario (UI): Ninguno Confidentiality (VC): Alto Integrity (VI): Alto Availability (VA): Alto Confidentiality (SC): Alto Integrity (SI): Alto Availability (SA): Alto

Puntuación base: 10.00 CRÍTICA Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Vector de acceso (AV): A través de red Complejidad de acceso (AC): Bajo Privilegios Requeridos (PR): Ninguno Interacción del usuario (UI): Ninguno Alcance (S): Modificado Impacto a la confidencialidad (C): Alto Impacto a la integridad (I): Alto Impacto a la disponibilidad (A): Alto

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Critical Authorization Vulnerability in SiYuan (CVE-2026-66012) 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, and enables attackers to read sensitive configuration files and execute arbitrary code with administrative privileges. The flaw is particularly dangerous when the Publish server is enabled in anonymous mode, as it allows attackers to plant malicious plugins that execute on desktop launch. A CVSS base score of 10 has been assigned, indicating critical severity. Currently, there is no evidence of active exploitation or public proof-of-concept available. Users are advised to upgrade to version 3.7.2 or later and review their workspaces for unauthorized files. The vulnerability was first published on July 25, 2026. 2 sources 78

Extracted Entities

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Extracted Entities

Attack Types (1)

CVEs (1)

CWE Weaknesses (1)