CVE-2026-126393

Description

SiYuan before 3.8.10 contains a server-side request forgery vulnerability in the skill-install download path because fetchBytes performs only a parse-time hostname check instead of using ssrfSafeClient. Attackers can supply a skill URL via the MCP skill install action that redirects or DNS-rebinds to loopback addresses, reaching internal services and metadata endpoints.

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

• 5.3CVSS 4.0, Mediumfrom the CNA (VulnCheck)CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
• 6.1CVSS 3.1, Mediumfrom the CNA (VulnCheck)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.

No explicit remediation statement is available on this page yet. Consult the original record and vendor references before choosing a fix.

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

Timeline

1. 13 Nov 2026 Published

Weakness

• CWE-918

References

• GitHub Security Advisory (GHSA-6pg3-pqxw-jm82)vendor-advisory
• VulnCheck Advisory: SiYuan before 3.8.10 SSRF via Skill-Install Download Redirect and DNS Rebindingthird-party-advisory