CVE-2026-59809CWE-201

CVE-2026-59809

Medium · published August 22, 2026

CVSS v3.1
4.9
EPSS
0%
Percentile
34.5
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
4.9 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
CVSS v4.0
6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
EPSS
0.00413 · 34.5th percentile
Weakness
CWE-201 · Insertion of Sensitive Information Into Sent Data
Published
2026-08-22T17:16Z
References (2)
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-853m-gvvm-6rvx · [email protected]https://www.vulncheck.com/advisories/siyuan-before-secret-exfiltration-via-http-request-url · [email protected]
EPSS history
Timeline
  • 22 AUG 12:26Z
    SiYuan before v3.8.0 Secret Exfiltration via http_request URL
    cvelistv5