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.
9.1of 10, critical
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.