The vulnerability stems from an insecure configuration in the crossdomain.xml file rather than specific code functions. Crossdomain.xml is a Flash policy file that controls cross-domain access, and an overly permissive configuration (e.g., allowing '*' as a trusted domain) enables untrusted Flash content to interact with the application. The vulnerability is configuration-related, not tied to a specific function in the codebase. No functions are explicitly mentioned in the provided CVE/GHSA descriptions or patch details, and the fix would involve modifying the crossdomain.xml content rather than altering code logic.