---
id: CVE-2026-59809
title: >-
  SiYuan before v3.8.0 interpolates secret placeholders into the destination URL
  parameter of the http_request MCP tool, allowing attackers to exfiltrate
  stored secrets
summary: >-
  SiYuan before v3.8.0 interpolates secret placeholders into the destination URL
  parameter of the http_request MCP tool, allowing attackers to exfiltrate
  stored secrets. An MCP client can craft a request with an attacker-controlled
  URL con…
severity: medium
cvss: 4.9
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-201
published: '2026-08-22'
updated: '2026-08-22'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-59809'
references:
  - url: >-
      https://github.com/siyuan-note/siyuan/security/advisories/GHSA-853m-gvvm-6rvx
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/siyuan-before-secret-exfiltration-via-http-request-url
    label: disclosure@vulncheck.com
tags:
  - nvd
ingestedAt: '2026-08-23T04:42:14.471Z'
epss: 0.00244
epssPercentile: 0.15845
---

## Overview

SiYuan before v3.8.0 interpolates secret placeholders into the destination URL parameter of the http_request MCP tool, allowing attackers to exfiltrate stored secrets. An MCP client can craft a request with an attacker-controlled URL containing secret placeholders to send plaintext secret values to any public host without confirmation.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.