ruby-on-rails-xss
Secure defaults for XSS prevention for Ruby on Rails
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Rules (14)

Checks if HTML escaping is globally disabled for JSON output. This could lead to XSS.

The syntax `<%== ... %>` is an alias for `html_safe`. This means the content inside these tags will be rendered as raw HTML. This may expose your application to cross-site scripting. If you need raw HTML, prefer using the more explicit `html_safe` and be sure to correctly sanitize variables using a library such as DOMPurify.

'content_tag()' bypasses HTML escaping for some portion of the content. If external data can reach here, this exposes your application to cross-site scripting (XSS) attacks. Ensure no external data reaches here. If you must do this, create your HTML manually and use 'html_safe'. Ensure no external data enters the HTML-safe string!

'html_safe()' does not make the supplied string safe. 'html_safe()' bypasses HTML escaping. If external data can reach here, this exposes your application to cross-site scripting (XSS) attacks. Ensure no external data reaches here.

'raw()' bypasses HTML escaping. If external data can reach here, this exposes your application to cross-site scripting (XSS) attacks. If you must do this, construct individual strings and mark them as safe for HTML rendering with `html_safe()`.

'render inline: ...' renders an entire ERB template inline and is dangerous. If external data can reach here, this exposes your application to server-side template injection (SSTI) or cross-site scripting (XSS) attacks. Instead, consider using a partial or another safe rendering method.

'render text: ...' actually sets the content-type to 'text/html'. If external data can reach here, this exposes your application to cross-site scripting (XSS) attacks. Instead, use 'render plain: ...' to render non-HTML text.

Detected manual creation of an ERB template. Manual creation of templates may expose your application to server-side template injection (SSTI) or cross-site scripting (XSS) attacks if user input is used to create the template. Instead, create a '.erb' template file and use 'render'.

Detected a template variable used in 'link_to'. This will generate dynamic data in the 'href' attribute. This allows a malicious actor to input the 'javascript:' URI and is subject to cross- site scripting (XSS) attacks. If using a relative URL, start with a literal forward slash and concatenate the URL, like this: 'link_to "Here", "/"+@link'. You may also consider setting the Content Security Policy (CSP) header.

Detected a unquoted template variable as an attribute. If unquoted, a malicious actor could inject custom JavaScript handlers. To fix this, add quotes around the template expression, like this: "<%= expr %>".

Detected a template variable used in an anchor tag with the 'href' attribute. This allows a malicious actor to input the 'javascript:' URI and is subject to cross- site scripting (XSS) attacks. If using a relative URL, start with a literal forward slash and concatenate the URL, like this: href='/<%= link =>'. You may also consider setting the Content Security Policy (CSP) header.

'content_tag' exhibits unintuitive escaping behavior and may accidentally expose your application to cross-site scripting. If using Rails 2, only attribute values are escaped. If using Rails 3, content and attribute values are escaped. Tag and attribute names are never escaped. Because of this, it is recommended to use 'html_safe' if you must render raw HTML data.

'html_safe' renders raw HTML. This means that normal HTML escaping is bypassed. If user data can be controlled here, this exposes your application to cross-site scripting (XSS). If you need to do this, be sure to correctly sanitize the data using a library such as DOMPurify.

'raw' renders raw HTML, as the name implies. This means that normal HTML escaping is bypassed. If user data can be controlled here, this exposes your application to cross-site scripting (XSS). If you need to do this, be sure to correctly sanitize the data using a library such as DOMPurify.