Session Hijacking

flarum/core is vulnerable to Session Hijacking. The vulnerability is due to improper scoping of cookies, allowing an attacker-controlled subdomain to set cookies for the parent domain...

CVE-2025-27794

Summary: CVE-2025-27794 affects Flarum versions prior to 1.8.10, where an attacker-controlled authoritative subdomain can set cookies for the parent domain, potentially enabling session hijacking on sibling subdomains. What is affected: Flarum core (pre-1.8.10) with cookies scoped to a parent dom...