{"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":0.15835,"slug":"CVE-2026-59809","body":"## Overview\n\nSiYuan 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":27,"depthScoreParts":{"impact":27,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}