The vulnerability stems from improper handling of the 'spring-security-redirect' parameter during logout processing. Spring Security's LogoutFilter handles redirects by reading this parameter and setting the Location header directly. In vulnerable versions, the parameter value was not properly sanitized for CRLF characters (\r\n), allowing attackers to craft URLs that inject malicious headers or split responses. The LogoutFilter's handle method is directly responsible for processing this parameter and constructing the redirect response, making it the primary vulnerable function. The CVE description explicitly mentions the logout functionality and parameter manipulation, aligning with this component's responsibility.