The vulnerability stems from incomplete prevention of double OGNL evaluation in forced evaluation scenarios (%{...}). Key functions were identified through: 1) Historical context from S2-061/CVE-2020-17530 fixes in Component.java 2) Struts architecture where tag attribute processing flows through Component.findValue() 3) TextParseUtil's role in expression interpolation 4) Advisory emphasis on forced evaluation bypassing previous mitigations. These functions represent the OGNL evaluation entry points that would appear in stack traces during exploitation attempts.