Vulnerability · Published Sep 26, 2026 · Assigned by VulnCheck

CVE-2026-100642SiYuan v2.1.0 before v3.8.4 Cross-Site Request Forgery via CheckAuth

High 7.6

In plain English

A high-severity security flaw in siyuan from siyuan-note. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities).

Severity (CVSS 3.1)7.6High

Exploit odds (30 days)0.1%top 97.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

SiYuan versions from v2.1.0 before v3.8.4 contain a cross-site request forgery vulnerability in the CheckAuth lock-screen pass-through branch that grants administrator access to loopback requests without validating Origin headers. Attackers can craft malicious web pages that force victims to terminate the kernel process, read workspace configuration and proxy settings, and trigger administrative actions via zero-credential cross-origin requests from the victim's browser.

Affected products (as reported)

Vendor	Product	Versions
siyuan-note	siyuan	2.1.0 – before 3.8.4

Weakness: CWE-346 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H

References

GitHub Security Advisory (GHSA-9gpj-3rm3-x42m) vendor-advisory
VulnCheck Advisory: SiYuan v2.1.0 before v3.8.4 Cross-Site Request Forgery via CheckAuth third-party-advisory