---
id: CVE-2026-100642
title: >-
  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
summary: >-
  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.
  Attack…
severity: high
cvss: 7.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H'
cwe:
  - CWE-346
vendor: siyuan-note
product: siyuan
affected:
  - siyuan >= 2.1.0 < 3.8.4
published: '2026-09-26'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T15:17:12.460'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100642'
references:
  - url: >-
      https://github.com/siyuan-note/siyuan/security/advisories/GHSA-9gpj-3rm3-x42m
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/siyuan-2.1.0-before-3.8.4-cross-site-request-forgery-via-checkauth
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/siyuan-note/siyuan/security/advisories/GHSA-9gpj-3rm3-x42m
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
epss: 0.00127
epssPercentile: 0.02382
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-30T14:45:17.397705Z'
ingestedAt: '2026-09-26T13:33:20.923Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.