CVE-2026-100642 SiYuan - Cross-Site Request Forgery

SiYuan v2.1.0 before v3.8.4 contains a cross-site request forgery vulnerability caused by lack of Origin header validation in the CheckAuth lock-screen pass-through branch, letting attackers perform administrative actions via victim's browser, exploit requires victim browser interaction.

CVSS base score 7.6 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.11% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Cross-Site Request Forgery
Impact
Broken Access Control
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H
Published
26 September 2026
Updated
15 October 2026
Weakness
CWE-346

Vendor fix

Update to version 3.8.4 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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