React.js Security Guide: Threats, Vulnerabilities, and Ways to Fix Them (2023)

At first glance, cybersecurity is not tangible. However, all the unique features, attractive user interfaces and flawless performance don't matter unless your application is safe. This sad statistic proves the above statement:

React.js Security Guide: Threats, Vulnerabilities, and Ways to Fix Them (1)

As you can see, withouta suitable security layer is in place, your application often falls victim to hacks and attacks, resulting in numerous rounds of testing and development. This also applies to applications based on React.js,the first most in demandWeb Library in 2022.

If React.js is an important part of your app's tech stack, you've come to the right place. As a company that has deployed over 100 web applications using a JavaScript technology stack, we know a thing or two about how to secure a React.js web application. That's why we've put together these handy tips for building secure React.js apps.

Table of contents

Why React.js: Top reasons to choose this JS library

React.js hardly needs a long introduction. As one of the most popular web development libraries, it is notable for its Document Object Model (DOM) approach, great flexibility and customizability, easy learnability, and supportive development community. However, these are not the only reasons forChoose React.js for your front-end development.

  • ease. Unlike heavyweight frameworks like Angular, React only provides a skeleton on which to build the app. Developers can choose which routing or state management library to use, making it easier for experienced programmers to use.
  • Large pool of talent and profitability.Another advantage is that building a React development team is quite easy due to the large pool of talent. In the case of React, you're unlikely to face a talent shortage if neededhire React.js developers– The library is used by more than30% of technology professionals worldwide. Hiring React.js developers is also a cost-effective solution. gladlylook at their salariesand get a better idea of ​​upcoming costs.
  • Freedom in the development of architecture.React.js does not force developers to follow Model-View-Controller (MVC) or Model-View-View-Model (MVVM) architecture when building a web interface. Instead, you can develop non-standard architectures to better meet the needs of the creative project. Additionally, React.js could be strengthened with Flux, a pattern that manages data flow in a React.js application, in case developers need a more structured solution.
  • Easy testing.Testing React.js apps is easier due to their modular nature, which means developers can test modules piece by piece, speeding up the process and avoiding critical errors.
  • Responsiveness and Performance.React.js stands out from other JS frameworks and libraries for its rendering performance due to its virtual DOM. There's also the Fiber algorithm, which came to us in version 16, which increased performance and brought many potential benefits. In addition, React itself does not create any security gaps. Instead, there are many tools available for developers to close potential security holes.

However, no tool has been invented that can guarantee ultimate and untouchable data security. React.js is no exception, so let's find out the most common React vulnerabilities and ways to fix them.

The most common React.js cyber attacks

Every time React.js updates, new vulnerabilities appear that go undetected. To that end, it's impossible to cover every possible cyberattack that React.js (as well as any framework) might be vulnerable to. However, these four are the most common. Let's examine them in more detail.

Cross-Site-Scripting (XSS)

XSS is an injection of malicious script into a web application's code. The browser picks up this script and interprets it as legitimate. After that, the malicious code is executed as part of an application. Here's the process when the attacker injects React XSS code to steal session cookies from users and visitors:

React.js Security Guide: Threats, Vulnerabilities, and Ways to Fix Them (2)

A successful XSS attack could allow the attacker to capture user input to steal user credentials and sensitive data from application pages, send requests to servers, and more. Most of the time, an unnoticed XSS can lead to the complete compromise of an application.

Like most modern frameworks, React.js offers built-in defenses against XSS. Unfortunately they are not 100% effective. XSS is still the most common JavaScript attack.

SQL Injection

XSS is often confused with SQL injection (SQLi). However, the two are not the same. Although both involve malicious code injection, XSS leaves users vulnerable, while SQL targets the application itself. Simply put, SQL targets the database and changes the way queries are answered. SQL injection is one of the most common cyber attacks that are used to access sensitive data, banking information, passwords, etc.

Distributed Denial of Service (DDoS)

DDoS attacks overwhelm a web application infrastructure with more traffic than it can handle. Its purpose is to make an application inaccessible and unavailable to its users. Some of the most common methods used to carry out DDoS attacks are UDP (User Datagram Protocol), ICMP (Internet Control Message Protocol), SYN (Synchronize), and HTTP (Hypertext Transfer Protocol) request flooding. Because a server and firewall must process and respond to each request, an attacker attempts to exhaust resources such as memory and CPU processing time.

Cross-Site Request Forgery (CSRF)

To perpetrate a CSRF attack, an attacker creates an email or web page that convinces the victim to issue a state change request in the web application. This can be, for example, transferring money or granting permissions. Typically, an attacker exploits invisible links or images (0x0 pixels) to make a GET request or a form for a POST or PUT request. JavaScript code provides another way to make these requests, but any modern browser will prevent this unless explicitly allowed on the web application server.

(Video) React Security Vulnerabilities How to Protect Your App and Fix Them

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JavaScript and Java are particularly vulnerable to this vulnerability. As the name suggests, a zip-slip attack involves replacing an archived file within the system with a malicious file. In this way, the attacker remotely overwrites executable files and changes the way they run on the user's computer. Zip Slip is one of the most dangerous cyber attacks as it makes the application vulnerable to traversal of path attacks and leaks sensitive data.

broken authentication

Broken authentication is another vulnerability that becomes especially threatening when business accounts are exposed. If successful, an attacker gains the same access rights as a victim, which means that depending on the level of access, such an attack could significantly impact the sustainability of the organization.

React.js vulnerabilities and fixes

As discussed above, XSS, DDoS, and CSRF are the most common cyberattacks web applications face. But what exactly allows malicious code to penetrate such applications? Next, we examine vulnerabilities specific to React.js and common to all frameworks and ways to fix them.

React.js vulnerabilities

When building a React-based app, make sure your software developers are aware of the following vulnerabilities:

  • Server-side rendering
  • Dangerous URI schemes
  • „DangerouslySetInnerHTML“
  • escape hatches

Let's take a closer look at each one.

Server-side rendering

One of the main benefits of React is SSR (Server Side Rendering). This feature ensures faster page loading, better performance and facilitates SEO promotion of a future app. Unfortunately, it makes React apps vulnerable to attacks. For this reason.

Most React applications use Redux for application state management, which uses JSON, a simple data exchange format, to set an initial state for the application:

React.js Security Guide: Threats, Vulnerabilities, and Ways to Fix Them (4)

This is dangerous because "JSON.stringify" does not recognize sensitive data or XSS code. While the example above also includes code to mitigate simple XSS attacks, it's by no means a panacea.

It's also worth noting that SSR gives attackers a way to exploit vulnerabilities in third-party NPM packages.


Dangerous URI schemes

URLs without an "http:" or "https:" protocol can allow malicious code to enter your React app. If this URL is encrypted, it is harmless. But if provided by a user, it poses a potential React XSS threat.

Unfortunately, React.j's security features do not prevent the use of such bindings during development or provide built-in defenses against potential threats. That means it depends on youdevelopment teamto keep a close eye on this potential security issue.


  • Avoid URLs as input. For example, you can create an app that accepts YouTube video IDs instead of YouTube video URLs.
  • If the above option is not possible, use proven third-party tools, such asClean URLNPM package to clean up these potentially dangerous links. Ensure that all members of your development team use the same cleanup code.


Sometimes developers need to render HTML code from untrusted sources (e.g. user input). The easiest way to render it in a browser is to assign it directly to the HTML inner attribute. Since it can cause XSS vulnerabilities, React.js restricts its use by enabling the "dangerouslySetInnerHTML" property.

Unfortunately, this property does not guarantee code security and generates all data, be it benign or dangerous. In fact, dangerouslySetInnerHTML's function is to notify a developer that the code assigned to them may not be secure. Also, it is assumed that developers will not use this feature without reading the documentation.

(Video) How to Scan, Analyze and Fix Security Vulnerabilities using NPM AUDIT & Retire.js.


  • Always clean up dynamic values ​​assigned to the dangerousSetInnerHTML propertyDOM cleaning. Wrap this behavior in a security component and encourage developers to use it.
  • Avoid using user-generated properties with the createElement API.

escape hatches

One of the main benefits of React is that it prevents developers from manually injecting data into the browser's DOM to render components. However, there are cases when developers need direct access to DOM elements. For such scenarios, React offers escapes like “findDOMNode” and “createRef”.

Because an escape hatch returns native DOM elements with their full API, your application can manipulate the element directly without going through React. This can lead to an XSS vulnerability.


  • Do not output the HTML code, only text.
  • If direct output is required, use the appropriate DOM APIs to generate HTML nodes.
  • Clean the data with DOMPurify before putting it on the page.

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Common web framework vulnerabilities

The React.js security features mentioned above are effective. But when it comes to preventing some of the most common cyberattacks, there is no single 100% effective solution. Although React.js stands out from the other libraries and frameworks, it is not immune to itcommon security concerns for all frameworks, if:

  • authentication issues
  • broken access control
  • Security Misconfigurations
  • Unreliable built-in layers of protection
  • Lack of end-to-end encryption
  • Third-Party Vulnerabilities

Let's take a closer look at these problems and their possible solutions.

authentication issues

Compared to the server side, the client side is exposed to multiple actions performed by the users. Because of this, client-side authentication and authorization are often compromised. How can these defects be prevented? Follow the checklist below:

  • Even the slightest discrepancy in authenticating different IDs and passwords will result in unauthorized users accessing the authentication information. To avoid discrepancies, ensure that the domain "WWW" header has a domain attribute that authenticates different users with separate code variables.
  • Use the authentication methods correctly. For example, make sure the "realm" attribute is set correctly in the WWW-Authenticate header.
  • Introduce multi-factor authentication.
  • Use cloud-native authentication such asAzure ADÖAWS Instant Messaging.
  • Ensure robust credential recovery procedures.

To further secure your React authentication, consider the following:

broken access control

Ensure that all required authorization constraints and restrictions are met. Ignoring this notice could allow any user to access unauthorized control functions. With that in mind, consider the following:

  • Provide only role-based authentication.
  • Restrict access to features.

Incorrect security configuration and insufficient monitoring

Unfortunately, no framework follows all security measures by default. Reacting is no exception. Vulnerabilities often appear as a result of incomplete security configurations or malformed HTTP headers. In view of this, it is important to integrate security tests into thedevelopment processand conduct regular vulnerability monitoring throughout the lifecycle of your application.

So how can you keep an eye on your React app's security settings? Here are some tips:

  • Configure your servers according to documentation and best practices.
  • Regularly review security-critical configurations to ensure they are configured according to official documentation and avoid newly discovered vulnerabilities in that particular software.
  • Carry out regular updates and upgrades in a timely manner.

The unreliably constructed protective layer

Even a mismatch of APIs can lead to the disclosure of sensitive data. To avoid this, follow our advice:

  • Disable automatic form caching and auto-completion features for security-critical UI components.
  • Update the encryption algorithms as soon as the latest version is available.

Lack of end-to-end encryption

Providing end-to-end encryption is crucial. This type of encryption protects data exchanged between end users, for example between a user's browser and its servers or between its distributed services. The lack of end-to-end encryption has been responsible for most data breaches2019.

Third-Party Vulnerabilities

In many cases, React simply has nothing to do with vulnerabilities in your application. Using third-party libraries, modules, APIs and frameworks can allow security vulnerabilities to creep into your application. Luckily, implementing the React web application security solutions listed below protects your application from these “externally-caused” vulnerabilities:

  • Before you integrate third-party components into your application, scan them for vulnerabilities.
  • Perform updates manually.
  • Check NPM packages for known vulnerabilitiesnpm-Audit.
  • Ensure that the old versions of the components are patched with the newer ones.
  • stay away from itmalicious packages.

React.js security checklist for other vulnerabilities and threats

DoS and DDoSScan the entire React app for known DDoS vulnerabilities during and after development. Install visitor badge. Use CAPTCHA or JS tests against DoS. Consider tools likecloud flareto defend against potential and ongoing DDoS attacks.
CSRF and arbitrary code executionUse JWT tokens for session management. Make sure your app only reads saved CSRF tokens. Ensure that only relevant headers are generated after authentication.
XXEAvoid serializing sensitive data. Make sure your XML parsers are up to date. CarrySAST-Toolsto scan your code for XXE.
SQLiValidate API call functions against their respective API schemas. Extract all incoming data or use verified ORMs.

How to secure your React.js application

There are several vulnerabilities in React.js, and most of them are also specific to other libraries and frameworks. The only way to make your React.js application as secure as possible is to consider security issues at every stage of the development process and pay double attention to security testing. In fact, building a well-protected web application requires a wealth of experience in both React.js development and cybersecurity.

(Video) How to manage Node.js vulnerabilities [11 of 26] | Node.js for Beginners

At Relevant, we pride ourselves on having a highly skilled React.js team under our roof. You, in turn, are very welcomeOutsource the development of your React.js projectand hire the best programmers with our help. Whether you are looking for Quality Control EngineersTest your existing React.js solutionor need experts to create one from scratch, taking all security measures into account, feel free to do sowrite us.

Is React.js safe?

Although there is no such thing as 100% secure technology, React.js has fewer security concerns compared to other JS tools. There are also some tips and tricks to create a more secure code base and protect an application from common vulnerabilities in the first place.

What are React.js security issues?

Dangerous URL schemes, flawed authentication, and server-side rendering are the top security issues for React.js.

(Video) Building Secure React Applications • Philippe De Ryck • GOTO 2019

Can a React website be hacked?

Unfortunately, any website can be hacked, and the technologies used to create it are not the only factors that make a website more or less vulnerable. React.js has some vulnerabilities, but there are also privacy practices that make your React app more secure.

Is React secure against XSS?

React is relatively secure against XSS, but there are some simple tactics to better protect your application from this vulnerability. For example, rendering data via JSX and using data cleansing libraries can be helpful.


How do I fix vulnerabilities in React app? ›

Checklist to Fix XSS Vulnerability in React Apps
  1. The easiest way of securing any React app from multiple XSS attacks is to employ WAF (Web Application Firewall) with the code. ...
  2. Developers can also disable the markups through which attackers can perform external code execution on React app.

How do I fix vulnerabilities in NPM React? ›

Try running npm update command. It will update all the package minor versions to the latest and may fix potential security issues. If you have a vulnerability that requires manual review, you will have to raise a request to the maintainers of the dependent package to get an update.

What are the common threats & vulnerabilities most React developers forget to secure against? ›

The most common React. js cyberattacks
  • Cross-Site Scripting (XSS) XSS is an injection of a malicious script into the code of a web application. ...
  • SQL Injection. ...
  • Distributed Denial of Service (DDoS) ...
  • Cross-Site Request Forgery (CSRF) ...
  • Zip Slip. ...
  • Broken Authentication. ...
  • React. ...
  • Сommon web frameworks vulnerabilities.
Dec 8, 2022

How do you ensure security in React JS? ›

Use data binding with curly braces {} and React will automatically escape values to protect against XSS attacks. However, this protection only helps when rendering textContent and non HTML attributes. Use JSX data-binding syntax {} to place data in your elements.


1. React Security Crash Course 2022
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3. 9. Securing Web Applications
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5. Hacking & Patching Node.js Security Vulnerabilities with Liran Tal - The Big Fix 2022 by Snyk
6. React Native Security | Addressing typical mistakes
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