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.
Published: 2026-09-26
Score: 8.2 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Sat, 26 Sep 2026 13:30:00 +0000

Type Values Removed Values Added
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.
Title SiYuan before v3.8.4 Authentication Bypass via Plaintext Session Cookie
Weaknesses CWE-319
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'}

cvssV4_0

{'score': 8.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N'}

Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-09-26T13:23:09.854Z

Reserved: 2026-09-26T02:31:42.100Z

Link: CVE-2026-100635

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-09-26T14:16:45.007

Modified: 2026-09-26T14:16:45.117

Link: CVE-2026-100635

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses