CVE-2026-126265

CVSS 9.1 (critical) · published 2026-11-13

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.

Weakness: CWE-307

Source: NVD CVE-2026-126265

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

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