SiYuan before 3.8.10 SSRF via Skill-Install Download Redirect and DNS Rebinding

published 2026-10-29 16d ago modified 2026-11-13 2d ago also EUVD-2026-125172 , GHSA-6pg3-pqxw-jm82

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository siyuan-note/siyuan. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss: 6.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits: 0; none known

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.

Patch / fix

fixed in 1

siyuan-note siyuan 3.8.10

Is CVE-2026-126393 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-14).

CVSS scores

assigned by	version	score	vector
CNA	4.0	5.3	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
CNA	3.1	6.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CNA	4.0	5.3	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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD	3.1	6.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products

siyuan-note siyuan

Classification

Weakness

CWE-918 Server-Side Request Forgery

References

github.com /siyuan-note/siyuan/security/advisories/GHSA-6pg3-pqxw-jm82
vendor-advisory, advisory
vulncheck.com /advisories/siyuan-before-3.8.10-ssrf-via-skill-install-download-redirect-and-dns-rebinding
third-party-advisory

Sources

CVE List CVE-2026-126393
NVD CVE-2026-126393
Maintainer advisory GHSA-6pg3-pqxw-jm82

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of siyuan-note/siyuan published their own advisory on GitHub. Reviewed sources take precedence over it.