CVE-2026-59809 — MEDIUM (4.9)

Vulnerability Description

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.

CVSS Score

4.9

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

HIGH

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

HIGH

Integrity

NONE

Availability

NONE

Related Weaknesses (CWE)

CWE-201

References

FAQ

What is CVE-2026-59809?

CVE-2026-59809 is a vulnerability with a CVSS score of 4.9 (MEDIUM). 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 reques...

How severe is CVE-2026-59809?

CVE-2026-59809 has been rated MEDIUM with a CVSS base score of 4.9/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-59809?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.