Language: Python
Label: vulnerable
CWE: CWE-79 \u2014 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Code:
    def render(self, value):
        return mark_safe(f'<span class="label color-block" style="background-color: #{value}">&nbsp;</span>')