Templates XSS security

Security measures against XSS attacks

To prevent XSS issues Magento recommends the following rules for escaping output in templates:

  • If a method indicates that the contents is escaped, do not escape: getTitleHtml(), getHtmlTitle() (the title is ready for the HTML output)

  • Type casting and php function count() don’t need escaping (for example echo (int)$var, echo (bool)$var, echo count($var))

  • Output in single quotes doesn’t need escaping (for example echo 'some text')

  • Output in double quotes without variables doesn’t need escaping (for example echo "some text")

  • For all other cases, escape the data using specific escape functions.

The following code sample illustrates the XSS-safe output in templates:

<?php echo $block->getTitleHtml() ?>
<?php echo $block->getHtmlTitle() ?>
<?php echo $block->escapeHtml($block->getTitle()) ?>
# <?php echo (int)$block->getId() ?>
<?php echo count($var); ?>
<?php echo 'some text' ?>
<?php echo "some text" ?>
<a href="<?php echo $block->escapeXssInUrl($block->getUrl()) ?>"><?php echo $block->getAnchorTextHtml() ?
></a>

Escape functions for templates

For the following output cases, use the specified function to generate XSS-safe output.

The upcoming release of Magento 2.2 will deprecate these functions.

Please check back on this page after the 2.2 release for updated documentation on new escape functions.

Case: JSON output
Function: No function needed for JSON output.

  <!-- In this example $postData is a JSON string -->
  <button class="action" data-post='<?php /* @noEscape */ echo $postData ?>' />

Case: String output that should not contain HTML
Function: escapeHtml

  <span class="label"><?php echo $block->escapeHtml($block->getLabel()) ?></span>

Case: URL output
Function: escapeUrl

  <a href="<?php echo $block->escapeUrl($block->getCategoryUrl()) ?>">Some Link</a>

Case: HTML attributes
Function: escapeQuote

  <span class="<?php $block->escapeQuote($block->getSpanClass()) ?>">Product Description</span>

Static Test

To check your template for XSS vulnerabilities, you can use the static test XssPhtmlTemplateTest.php in dev\tests\static\testsuite\Magento\Test\Php\.

This static test finds all echo calls in PHTML-templates and determines if the output is properly escaped.

It covers the following cases:

  • /* @noEscape */ before output. Output doesn’t require escaping. Test is green.

  • /* @escapeNotVerified */ before output. Output escaping is not checked and should be verified. Test is green.

  • Methods which contain "html" in their names (for example echo $object->{suffix}Html{postfix}()). Data is ready for the HTML output. Test is green.

  • AbstractBlock methods escapeHtml, escapeUrl, escapeQuote, escapeXssInUrl are allowed. Test is green.

  • Type casting and php function count() are allowed (for example echo (int)$var, (bool)$var, count($var)). Test is green.

  • Output in single quotes (for example echo 'some text'). Test is green.

  • Output in double quotes without variables (for example echo "some text"). Test is green.

  • Other of previously mentioned. Output is not escaped. Test is red.