CVE-2026-126265

EUVD-2026-125256
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
7.4 HIGH
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Awaiting analysis
This vulnerability is currently awaiting analysis.
Base Score
CVSS 3.x
EPSS Score
Percentile: 29.81%
Common Weakness Enumeration
References
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-23g4-vqq8-5764
https://www.vulncheck.com/advisories/siyuan-2.1.0-before-3.8.9-captcha-bypass-via-stale-login-cookie