---
id: CVE-2026-100635
title: >-
  SiYuan before v3.8.4 contains an authentication bypass vulnerability in the
  publish service where session cookies are issued without Secure or SameSite
  attributes over plaintext HTTP connections
summary: >-
  SiYuan before v3.8.4 contains an authentication bypass vulnerability in the
  publish service where session cookies are issued without Secure or SameSite
  attributes over plaintext HTTP connections. An on-path attacker can observe a
  valid p…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-319
vendor: siyuan-note
product: siyuan
affected:
  - siyuan < 3.8.4
published: '2026-09-26'
updated: '2026-09-26'
sourceUpdated: '2026-09-26T14:16:45.117'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100635'
references:
  - url: >-
      https://github.com/siyuan-note/siyuan/commit/79d47867b106467c951475a9193455b48d1f3682
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/siyuan-note/siyuan/commit/ff4d215f78a8d6e6db6052be18b5f9f4db9c7d68
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/siyuan-note/siyuan/security/advisories/GHSA-7j37-4gq6-wm7m
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/siyuan-before-3.8.4-authentication-bypass-via-plaintext-session-cookie
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-26T13:33:20.925Z'
---

## Overview

SiYuan before v3.8.4 contains an authentication bypass vulnerability in the publish service where session cookies are issued without Secure or SameSite attributes over plaintext HTTP connections. An on-path attacker can observe a valid publish-visitor-session-id cookie from a Basic Auth exchange and replay it to access authenticated publish endpoints without knowing the account password.

## Remediation

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