XSS vulnerability in DateTimePicker Component due to lack of xml escaping

During some security tests, we concluded that although DateTimePicker escapes XML content in value field, the same is used in the generated script, in date field, without escaping. This allows cross site scripting and unwanted code may be run by malicious actions.

Checkout the following examples. Here we forced the value (by editing the Html) with a js script.
In the renderer generated code, markup code is escaped here:
<input type="text" id="myform:myperiod_Input" name="myform:myperiod" class="form-control bf-required" placeholder="aaaa - mm" value="2020 - 02--></sCrIpT><sCrIpT>alert(51845)</sCrIpT>" />

And here, it is not.
</script><script>$(function () { $('#myform\\:myPeriodOuter').datetimepicker({ ignoreReadonly: false, allowInputToggle: true, collapse: true, dayViewHeaderFormat: 'MMMM YYYY', focusOnShow: true, minDate: '2020-01', maxDate: '2020-03-30', stepping: 1, toolbarPlacement: 'default', viewMode: 'days', useCurrent:false,date: moment('2020 - 02--></sCrIpT><sCrIpT>alert(51845)</sCrIpT>', 'YYYY - MM'), locale: 'pt', format: 'YYYY - MM'});});</script>

This is due to the following:
In DateTimePickerRenderer the value is written via writeAttribute method of ResponseWriter class, that ensures that markup code is escaped.

BootsFaces-OSP/src/main/java/net/bootsfaces/component/dateTimePicker/DateTimePickerRenderer.java

Lines 261 to 262 in c8ca2c3

    
           if (v != null) { 
        
           	rw.writeAttribute("value", getValueAsString(v, fc, dtp), null);

In the generated script, the renderer gets the value and no escaping is performed. getValueAsString calls getDateAsString, and this calls getInternalDateAsString that returns a formated date, or getAsString from a custom converter (which is our case).

BootsFaces-OSP/src/main/java/net/bootsfaces/component/dateTimePicker/DateTimePickerRenderer.java

Lines 392 to 393 in c8ca2c3

    
           String inlineDisplayDate = "'" + 
        
           		getValueAsString(v, fc, dtp) + "'";

BootsFaces-OSP/src/main/java/net/bootsfaces/component/dateTimePicker/DateTimePickerRenderer.java

Line 435 in c8ca2c3

"date: moment(" + inlineDisplayDate + ", " + displayFormat + "), " +

Thanks

That doesn't sound good. I can't promise anything, but I intend to have a close look at this bug this week-end. Thanks for pointing this out and for your thorough analysis!

I've just fixe. the bug by adding the OWASP HTML sanitizer. I've published a new 1.5.0-SNAPSHOT on Maven Central. Can you check if this fixes the vulnerability?

Thanks in advance,
Stephan

	if (v != null) {
	rw.writeAttribute("value", getValueAsString(v, fc, dtp), null);

	String inlineDisplayDate = "'" +
	getValueAsString(v, fc, dtp) + "'";