CVE-2026-59809: Insertion of Sensitive Information Into Sent Data in siyuan-note siyuan
Description
SiYuan note-taking software versions prior to 3.8.0 contain a vulnerability where secret placeholders are interpolated into the destination URL parameter of the http_request MCP tool. This allows an attacker controlling an MCP client to craft requests that exfiltrate plaintext secret values to arbitrary external hosts without user confirmation.
CVSS v4.0
Score 6.9medium
Affected software
siyuan-note
siyuan
pkg:github/siyuan-note/siyuanRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-59809 affects SiYuan versions before 3.8.0. The vulnerability arises from the interpolation of secret placeholders into the destination URL parameter of the http_request MCP tool. An attacker with MCP client privileges can create a request with a URL containing secret placeholders, causing stored secrets to be sent in plaintext to any public host controlled by the attacker, bypassing confirmation mechanisms.
Potential Impact
Attackers can exfiltrate sensitive information stored within SiYuan by leveraging the http_request MCP tool to send secrets in plaintext to arbitrary external hosts. This compromises confidentiality of stored secrets. The vulnerability requires attacker control of an MCP client and does not involve user interaction, increasing risk in environments where MCP clients are accessible.
Mitigation Recommendations
A fixed version (3.8.0) of SiYuan is available that addresses this vulnerability. Users should upgrade to version 3.8.0 or later to remediate the issue. No additional mitigation guidance is provided or required beyond applying the official fix.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-07-07T14:39:14.063Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a899b98acd9273b490877fe
Added to database: 08/22/2026, 12:52:40 UTC
Last enriched: 09/11/2026, 02:03:11 UTC
Last updated: 10/06/2026, 18:48:23 UTC
Views: 60
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