---
id: "CVE-2026-123492"
page: "https://infrastack.ai/live/CVE-2026-123492"
kind: "vulnerability"
aliases: ["CVE-2026-123492"]
title: "SiYuan: MCP resource read crashes the kernel for authenticated users"
severity: "medium"
cvss: 6.9
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["mcp", "package", "self-hosted", "siyuan"]
not_affected_if: ["mcp-disabled", "no-api-token-access"]
published_at: "2026-11-06T15:17:18+00:00"
first_seen_at: "2026-11-06T15:42:44+00:00"
updated_at: "2026-11-06T15:44:24+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123492", "first_seen_at": "2026-11-06T15:42:44+00:00"}]
exploit_sources: []
---

# SiYuan: MCP resource read crashes the kernel for authenticated users

Link for people: https://infrastack.ai/live/CVE-2026-123492 (this .md is for agents)

SiYuan before 3.8.9 has a nil pointer dereference in privateCacheMiddleware. An attacker with a valid API token can send a resources/read request for a nonexistent MCP resource, which panics and terminates the kernel process, interrupting service.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed SiYuan version in the app's About panel or package metadata; versions below `3.8.9` are in range.
- Confirm whether the MCP server is enabled and reachable by clients that hold API tokens.

## Fix

- SiYuan: move to `3.8.9` or later.

## Timeline

- 2026-11-06T15:42:44+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123492

## Documents

- [advisory] Vendor advisory: github.com https://github.com/siyuan-note/siyuan/security/advisories/GHSA-2x3p-x74g-442x
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/siyuan-before-3.8.9-nil-pointer-dereference-dos-via-mcp-resources-read

## From the sources

SiYuan before 3.8.9 contains a nil pointer dereference vulnerability in privateCacheMiddleware that allows authenticated attackers to crash the kernel by reading nonexistent MCP resources. Attackers with a valid API token can send a resources/read request in an initialized MCP session, causing a panic that terminates the kernel process and interrupts service.

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_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_