CVE-2026-123535: Security vulnerability

Tornado before 6.6 does not validate the maxage argument of RequestHandler.setcookie (also called by setsignedcookie, setsecurecookie, and clearcookie), allowing injection of additional Set-Cookie attributes. When an application passes attacker-influenced input as maxage, an attacker can embed attributes such as Domain, Path, or Secure to widen the cookie's scope to parent paths or other subdomains.