CVE-2026-100642 SiYuan v2.1.0 before v3.8.4 Cross-Site Request Forgery via CheckAuth
Attackers can exploit CSRF in SiYuan to gain admin access, read configs, and crash the kernel via malicious web pages.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-100642?
CVE-2026-100642 is a high-severity vulnerability in siyuan-note siyuan, published on 26 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
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.
Weakness: CWE-346
Which versions are affected by CVE-2026-100642?
How do I fix CVE-2026-100642?
No fix has been published for CVE-2026-100642 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-100642 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100642 exists.
Sources
Also known as GHSA-8r4c-c246-mwjc, GHSA-9gpj-3rm3-x42m.