HtmlEncodeModelBinder.cs

public class HtmlEncodeModelBinder : IModelBinder
{
    private readonly IModelBinder _fallbackBinder;

    public HtmlEncodeModelBinder(IModelBinder fallbackBinder)
    {
        if (fallbackBinder == null)
            throw new ArgumentNullException(nameof(fallbackBinder));

        _fallbackBinder = fallbackBinder;
    }
    
    public Task BindModelAsync(ModelBindingContext bindingContext)
    {
        if (bindingContext == null)
            throw new ArgumentNullException(nameof(bindingContext));

        var valueProviderResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
        
        if (valueProviderResult == ValueProviderResult.None)
        {
            return _fallbackBinder.BindModelAsync(bindingContext);
        }

        var valueAsString = valueProviderResult.FirstValue;

        if (string.IsNullOrEmpty(valueAsString))
        {
            return _fallbackBinder.BindModelAsync(bindingContext);
        }

        var result = HtmlEncoder.Default.Encode(valueAsString);
        bindingContext.Result = ModelBindingResult.Success(result);
       
        return Task.CompletedTask;
    }
}