CVE-2024-45614 is a vulnerability in Puma's header normalization that allows clients to override headers set by intermediate proxies by using underscore variants of header names. This can affect users who trust proxy-set headers, potentially enabling attackers to downgrade connections to HTTP or redirect responses, risking confidentiality if combined with a MITM attack. Fixed versions 5.6.9 and 6.4.3 discard underscore headers when the non-underscore version exists. Users relying on proxy headers for security should upgrade immediately or configure proxies like Nginx to discard underscore headers.