The vulnerability centers around the merge functionality as explicitly stated in all advisory descriptions. While the actual patch code isn't shown, the Snyk report provides a clear proof-of-concept using mergeDeep and the CVE description specifically mentions the merge method. This function would appear in runtime profiling when processing malicious merge operations. The lack of prototype chain checks in object property merging (visible in the PoC's ability to set proto properties) makes mergeDeep the primary vulnerable function.