Secuno
ENNL
Book demo

CVE-2026-66012

SiYuan broken access control

10.0 CRITICALEPSS 0.76%
  1. Published25 Jul 2026

Description

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 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeChanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

CVE-2026-891089.1
SAP Manufacturing Integration and Intelligence does not sufficiently enforce…
CVE-2026-1096408.1
Frappe ERPNext before 16.22.0 contains a missing authorization vulnerability that…
CVE-2026-843158.3
Nginx UI is a web user interface for the Nginx web server. Prior to 2.4.1, Nginx UI…
CVE-2026-571189.8
PraisonAI is a multi-agent teams system. Prior to praisonaiagents 1.6.59,…
CVE-2026-1092018.3
LogicalDOC Community Edition through 9.3 contains a missing authorization vulnerability…
CVE-2026-1091858.8
jshERP through 3.6 contains a missing authorization vulnerability in the UserController…

Frequently asked

Is CVE-2026-66012 being actively exploited?

CVE-2026-66012 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.76%.

How severe is CVE-2026-66012?

CVE-2026-66012 has a CVSS 3.1 base score of 10.0, rated critical. EPSS estimates a 0.76% probability of exploitation.

How do I fix CVE-2026-66012?

Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-66012 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

See how prioritisation worksBook a demo

Get Patch this first every Monday

Five vulnerabilities that matter this week, ranked on real exploitation. Plain language, one email, no spam.

You can unsubscribe with one click from every issue. We handle your details as described in our privacy policy.

Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.