All vulnerabilities
CVE-2026-100635GHSA-7j37-4gq6-wm7m

SiYuan before v3.8.4 Authentication Bypass via Plaintext Session Cookie

siyuan-note siyuan
Open in ThreatlineRecord JSON
CVSS
8.2High
ExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 28 Sep 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.26%Chance of exploitation activity in the next 30 days, higher than 16% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in3.8.4Fixed versionCVE List
Published26 Sep 2026Updated 8 Oct 2026CVE List

What fixes it

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

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.

Text from CVE List

Affected versions 2

  • siyuanaffected: all versions before 3.8.4CVE List
  • siyuanunaffected: 3.8.4CVE List

References 4