i18next is a language translation framework. Because of how the interpolation is implemented, making replacements from the dictionary one at a time, untrusted user input can use the name of one of the dictionary keys to inject script into the browser. This affects i18next <=1.10.2.

Affected: npm: i18next

Affected versions of `i18next` allow untrusted user input to be injected into dictionary key names, resulting in a cross-site scripting vulnerability.

## Proof of Concept ```js var init = i18n.init({debug: true}, function(){ var test = i18n.t('__firstName__ __lastName__', { escapeInterpolation: true, firstName: '__lastNameHTML__', lastName: '<script>', }); console.log(test); }); // equals "<script> &lt;script&gt;" ```

## Recommendation

Update to version 1.10.3 or later.