CVE-2026-72721: Improper Handling of Case Sensitivity

Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, Onebox::DomainChecker.isblocked? compares hostnames and SiteSetting.blockedoneboxdomains entries case-sensitively, allowing an attacker to bypass configured Onebox domain restrictions by changing...