Security issues identified in 2016 on the Equifax website are still not fixed. It is one step to identify the problem but it's an even bigger challenge to fix it. It requires time and skill to go back into the code, understand the context and fix the issues.

It is clear developers at Equifax were under a lot of stress and many known vulnerabilities didn’t get fixed. Unfortunately that lack of action has now had the worst possible response. 

Security needs to be baked in from the start and developers needs the skills, training and in-IDE tools to minimize writing known vulnerabilities. It requires specific language and framework knowledge to fix the problems identified. The general principle on fixing a XSS issue stays the same, however the actual implementation is dependent on the frameworks in place.

If you want to do some interactive training on how to fix XSS issues in Struts, check out: https://portal.securecodewarrior.com/#/simple-flow/web/xss/reflected/java/struts