search portlet included in a theme does not generate its URLs escaped

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 6.0.12 EE, 7.0.0 M3
• Fix Version/s: 6.0.X EE, 6.1.X EE, 6.2.2 CE GA3 , 6.2.X EE, 7.0.0 M1
• Component/s: Frontend Infrastructure, Frontend Infrastructure > UI Taglibs, Security Vulnerability
• Labels:
  • QA-KC
  • QA-TP
  • liferay-fixpack-search-3-6130
  • liferay-fixpack-search-7-6210
• Branch Version/s:
  6.2.x, 6.1.x, 6.0.x
• Backported to Branch:
  Committed
• Story Points: 10
• Fix Priority: 4
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/17909

STEPS TO REPRODUCE
1.- Modify a theme to include this line to place the search portlet:
$theme.search()
2.- Refresh the page
3.- Get the HTML source from the browser

ACTUAL RESULT

<form action="http://localhost:8080/web/guest/home?p_p_id=3&p_p_lifecycle=0&p_p_state=maximized&p_p_mode=view&_3_struts_action=%2Fsearch%2Fsearch&_3_redirect=%2Fweb%2Fguest%3Fstrip%3D0" method="get" name="fphf_null_null_3_fm" onSubmit="fphf_null_null_3_search(); return false;">

The & character is not escpaed, making the W3C validation to fail

EXPECTED RESULT
The & should be generated as

&