Cross site scripting via Bootstrap
Description
Cross-Site Scripting (XSS) is a client-side code injection vulnerability that allows attackers to execute malicious scripts in a victim's browser within the context of a trusted website. This vulnerability affects applications using certain versions of the Bootstrap framework, which implemented jQuery plugins in an unsafe manner. The core issue stems from Bootstrap's use of jQuery's $() function in contexts where it evaluates user-controlled input as JavaScript code rather than treating it as a safe CSS selector, creating opportunities for XSS attacks when processing data attributes or other user-supplied values.
Remediation
Take the following steps to remediate this vulnerability:
1. Upgrade Bootstrap: Update to Bootstrap version 3.4.0 or later (for Bootstrap 3.x users) or Bootstrap 4.1.2 or later (for Bootstrap 4.x users). These versions contain fixes for the XSS vulnerabilities in data attribute handling.
2. Verify the Update: After upgrading, confirm the Bootstrap version in your package.json, bower.json, or by checking the version comment in the bootstrap.js file:
// Check package.json "bootstrap": "^4.1.2" or "^3.4.0"
3. Review Custom Code: If you have custom JavaScript that uses Bootstrap's data-API or jQuery plugins, ensure you are not passing unsanitized user input to jQuery's $() function. Use safer alternatives like document.getElementById() or jQuery's .find() method when working with user-controlled data.
4. Implement Content Security Policy: As an additional defense-in-depth measure, implement a Content Security Policy (CSP) header to mitigate the impact of any XSS vulnerabilities:
Content-Security-Policy: default-src 'self'; script-src 'self'
5. Test Thoroughly: After upgrading, test all Bootstrap components and data-attribute functionality to ensure compatibility and proper operation.