SiYuan 2.1.0 before 3.8.9 CAPTCHA Bypass via Stale Login Cookie
Not on CISA's list of exploited flaws, and not in the news we track.
0.36%
Reading the vendor advisory
Fix it in your code
Each opens with a short prompt that points at Global Hack Map's public runbook for CVE-2026-126265. Nothing runs until you send it.
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.
You are affected if
The fix