DOMPurify VS Next.js

DOMPurify

I saw that some people were injecting alerts. If you haven't fixed it yet, consider using something like DOMPurify to sanitize the HTML input before posting it to the db.

You mean from this article "Sanitize HTML strings"? https://phuoc.ng/collection/html-dom/sanitize-html-strings/

Yeah, that article really shouldn't imply that sanitization is "that easy". It does at least mention https://github.com/cure53/DOMPurify at the end but it should LOUDLY argue against attempting to write this particular thing yourself and promote that exclusively in my opinion.

It is highly recommended to use an XSS Sanitizer like DOMPurify to sanitize HTML and prevent XSS attacks. For Next.js projects, which prominently feature server-side rendering, Isomorphic DOMPurify is especially valuable. It offers a seamless sanitization process across both server and client, ensuring consistent HTML sanitization in environments like Next.js where a native server-side DOM isn't present.

Note: We’ve used DOMPurify to sanitize the HTML in the above code block. You can install it in Node.js with npm install dompurify. Include it in your HTML with .

body, input.value property, or body are all different). If you need to insert untrusted input into raw HTML, use a well-tested sanitizer such as DOMPurify.

Setting a strong Content Security Policy without unsafe-inline or unsafe-eval in the script-src or default-src directives is an effective defense-in-depth) measure to prevent modern browsers from executing attacker code even if the attacker is able to insert </code> elements into the page.</p> <p><strong>3. HTTP API injection</strong></p> <p>RESTful APIs, GraphQL, and other HTTP-based APIs are ubiquitous. When a web application makes an API call to another service, injection vulnerabilities are possible when that request includes untrusted input.</p> <p>Consider a contrived example in which a web app integrates with a payments service that has a REST API endpoint for creating a subscription: <code>POST /subscriptions/{product_id}?price_usd=<price></code> where <code>price_usd</code> is optional, and a pre-configured price is used if omitted. If an attacker controls the value of <code>product_id</code> and passes a value of <code>desired_product_id?price_id=0</code>, the web app would end up making a request to <code>POST /subscriptions/desired_product_id?price_id=0</code>, which would allow the attacker to sign up for a free subscription.</p> <p>In JavaScript, the standard way to sanitize untrusted inputs in URL paths is <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent"><code>encodeURIComponent</code></a>, which replaces problematic characters such as <code>?</code> and <code>/</code> with safe percent-encoded sequences. When inserting untrusted input into URL query parameters, <a href="https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams/URLSearchParams"><code>new URLSearchParams(queryParams)</code></a> provides a convenient, safe interface for building a query string from a JavaScript object of key-value pairs.</p> <p><strong>4. Shell injection</strong></p> <p>Backend APIs sometimes need to execute external commands on the machine where they run. Consider an API that performs <a href="https://en.wikipedia.org/wiki/WHOIS">WHOIS</a> lookups for a requested domain by executing the <code>whois</code> command locally.</p> <p>Consider the following <strong>vulnerable</strong> Node.js code:</p> <pre><code>const whois = child_process.execSync(`whois ${whoisRequest.domain}`); </code></pre> <p>If an attacker can pass the domain <code>reddit.com && rm -rf /</code>, the backend will execute the command <code>whois reddit.com && rm -rf /</code>. The <a href="https://nodejs.org/api/child_process.html#child_processexecsynccommand-options"><code>child_process.execSync</code></a> function passes the command string to the shell (<code>/bin/sh</code> by default on Linux), which parses <code>&& rm -rf /</code> as a subsequent command to wipe the filesystem.</p> <p>To avoid this issue, <strong>never pass untrusted input to a shell</strong>. Instead, use an interface such as <a href="https://nodejs.org/api/child_process.html#child_processexecfilesyncfile-args-options"><code>child_process.execFileSync</code></a> that executes a specific binary (which shouldn't be a shell!) and passes arguments <em>as an array</em>:</p> <pre><code>const whois = child_process.execFileSync("whois", [whoisRequest.domain]); </code></pre> <p>Now, even if the user passes a domain <code>reddit.com && rm -rf /</code>, that entire string will be passed as the command-line argument to <code>whois</code>, which will exit with an error but will not cause any harmful side-effects. Perhaps an even better solution would be to use a library to perform WHOIS queries without needing to execute a separate command.</p> <p>Astute readers may point out that validating the domain against a regex would also likely prevent shell injection in this case. However, avoiding the possibility of shell injection by using a safe interface that keeps untrusted input away from a shell's command parser is a more robust solution that avoids shell injection in all cases.</p> <p><strong>5. Path traversal</strong></p> <p>Finally, a path traversal vulnerability arises when an untrusted input is inserted into a filesystem path, which can cause the wrong file to be read or even written. Consider a backend API that reads a file at the path <code>/teams/${team_id}/${report_name}.csv</code>. If an attacker controls the value of <code>report_name</code> but not <code>team_id</code>, they could pass a <code>report_name</code> of <code>../other_team_id/private.</code> This would cause the file <code>/teams/team_id/../other_team_id/private.csv</code> (resolved to <code>/teams/other_team_id/private.csv</code>) to be read, leaking data from a different team.</p> <p>To avoid path traversal vulnerabilities, <strong>never use untrusted input in file or directory names</strong>. It's safest always to control the names of files and directories, including IDs that you generate and control (e.g., UUIDs, KSUIDs, etc.). If the name of a file or directory absolutely <em>must</em> be derived from untrusted input, consider hashing it (e.g., using SHA-256) or at least encoding it into a format that doesn't include dots or slashes (e.g., <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-5">URL-safe base64</a>).</p> <p>​</p> <p>Know of good Node.js libraries for avoiding injection vulnerabilities? Let folks know in the comments!</p> </div><!-- SC_ON -->

https://stackoverflow.com/questions/43584685/input-sanitization-in-reactjs https://www.npmjs.com/package/dompurify

If you're using an external view engine, or a javascript framework like react in addition to your ruby backend, you can rely on similar sanitization methods like the DOMPurify library.

You shouldn't roll your own for this. From what I've had to do web-wise, here's a few tools.

First, for the APIs, you need documentation: https://swagger.io/

From which you can generate JSON schemas and use those to validate in the browser and on the backend. https://www.npmjs.com/package/jsonschema

As well you should be writing a few more schemas for your application state and leverage the regex validation of your input components...

Speaking of which, you also need to sanitize out some potentially nasty input. https://www.npmjs.com/package/dompurify

Obviously this isn't everything and not perfect, but a lot of this tedium can be automated away if you have a few good examples of the happy path and some basic tests in place to prevent quick and dirty changes from poking holes in these layers.

Next.js has long cemented itself as one of the front runners in the web framework world for JavaScript/TypeScript projects so we’re going to be using that. More specifically we’re going to be using V14 of Next.js which allows us to use some exciting new features like Server Actions and the App Router.

Web frameworks like Next.js will usually include this feature, but do check that they set the caching headers correctly!

Vite and Next.js are both top 5 modern development framework right now. They are both great depending on your use case so we’ll discuss 4 areas: Architecture, main features, developer experience and production readiness. After learning about these we’ll have a better idea of which one is best for your project.

> It’s important to be aware of what you are getting if you go with React, and what you are getting is a far cry from what a framework would offer, with all the corresponding pros and cons.

Would you like to elaborate on that?

In my experience, with something as great, size/ecosystem-wise as React, there will almost always be at least one "mainstream" package for whatever you might want to do with it, that integrates pretty well. Where a lot of things might come out of the box with a framework, with a library I often find myself just needing to install the "right" package, and from there it's pretty much the same.

For example, using https://angular.io/guide/i18n-overview or installing and using https://react.i18next.com/

Or something like https://angular.io/guide/form-validation out of the box, vs installing and using https://formik.org/

Or perhaps https://angular.io/guide/router vs https://reactrouter.com/en/main

Even adding something that's not there out of the box is pretty much the same, like https://primeng.org/ or https://primereact.org/

React will typically have more fragmentation and therefore also choice, but I don't see those two experiences as that different. Updates and version management/supply chain will inevitably be more of a mess with the library, admittedly.

Now, projects like Next https://nextjs.org/ exist and add what some might regard as the missing pieces and work well if you want something opinionated and with lots of features out of the box, but a lot of those features (like SSR) are actually pretty advanced and not always even necessary.

Next.js: For the website and the admin dashboard

Until the time of writing, there is no official example of how to enable runtime environmental variables in a Dockerized Next.js app, as utilizing unstable_noStore would only dynamically evaluate variables on the server (node.js runtime). There is also an interesting discussion regarding this topic on GitHub.

next.js is a very popular React framework. remix-adonisjs includes more functionality through the AdonisJS backend ecosystem, and should be easier to self-host and self-manage.

Cheryl Murphy is not only a dedicated full-stack web developer skilled in technologies like React, Next.js, and NestJs but also a community-driven professional who recently took on the role of volunteer project team lead at Web Dev Path. With a dual Bachelor's degree in Computing and Chemical Engineering from Monash University, Cheryl’s journey in tech is marked by a passion for building accessible solutions and a commitment to fostering community within tech.

For more information, check out this issue.

Remember to start the Next.js server with pnpm dev.