Description
SiYuan 2.1.0 before 3.8.9 contains a flaw where the loginAuth CAPTCHA challenge lives in a signed client-side cookie, allowing reuse of a solved challenge. Attackers can replay the original signed siyuan cookie with distinct wrong access codes to brute-force the code and gain an administrator session.
Published: 2026-11-13
Score: 9.1 Critical
EPSS: n/a
KEV: No
AI Analysis

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Remediation

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Tracking

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Advisories

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History

Fri, 13 Nov 2026 09:45:00 +0000

Type Values Removed Values Added
Description SiYuan 2.1.0 before 3.8.9 contains a flaw where the loginAuth CAPTCHA challenge lives in a signed client-side cookie, allowing reuse of a solved challenge. Attackers can replay the original signed siyuan cookie with distinct wrong access codes to brute-force the code and gain an administrator session.
Title SiYuan 2.1.0 before 3.8.9 CAPTCHA Bypass via Stale Login Cookie
First Time appeared B3log
B3log siyuan
Weaknesses CWE-307
CPEs cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*
Vendors & Products B3log
B3log siyuan
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

cvssV4_0

{'score': 9.1, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'}

Subscriptions

B3log Siyuan
cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-11-13T09:36:50.432Z

Reserved: 2026-11-10T20:13:22.556Z

Link: CVE-2026-126265

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses