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CVE-2026-59809

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.

Published Aug 22, 2026CWE-201EPSS 0.41%

Overview

CVE-2026-59809 is a medium-severity vulnerability. It was published on August 22, 2026 and has a CVSS 3.1 base score of 4.9 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 4.9, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/siyuan-note/siyuan/security/advisories/GHSA-853m-gvvm-6rvxRefwww.vulncheck.com/advisories/siyuan-before-secret-exfiltration-via-http-request-url

How CyberStrike helps

Frequently asked questions

What is CVE-2026-59809?

CVE-2026-59809 is a medium-severity vulnerability. It was published on August 22, 2026 and has a CVSS 3.1 base score of 4.9 (MEDIUM).

How severe is CVE-2026-59809?

This vulnerability has a CVSS 3.1 base score of 4.9, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-59809?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-59809?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-59809 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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