React Router DOM versions 7.5.1 and 7.5.0 offer declarative routing solutions tailored for React web applications, enabling developers to manage navigation and create single-page applications with ease. Both versions, maintained under the MIT license by Remix Software, share a common foundation, including core dependencies like React Router and development tools such as tsup, react, react-dom, wireit, and typescript. They maintain peer dependency requirements, mandating React and React DOM versions of 18 or higher, ensuring compatibility with modern React environments.
However, a key distinction lies in their versions of the underlying React Router dependency, where version 7.5.1 depends on React Router version 7.5.1, while version 7.5.0 accordingly depends on React Router 7.5.0. This indicates that version 7.5.1 incorporates updates and potentially bug fixes directly related to the core React Router library that are not present in the previous version. While file count and unpacked size remain consistent between the versions, the significant difference is marked by the release dates, with 7.5.1 released on 2025-04-17 and 7.5.0 on 2025-04-04. Developers should prioritize version 7.5.1 to benefit from the latest fixes and improvements integrated within the React Router core. Furthermore, the newer version is backward compatible so it is definitely the first choice when thinking about upgrading react-router-dom.
All the vulnerabilities related to the version 7.5.1 of the package
React Router allows pre-render data spoofing on React-Router framework mode
After some research, it turns out that it's possible to modify pre-rendered data by adding a header to the request. This allows to completely spoof its contents and modify all the values of the data object passed to the HTML. Latest versions are impacted.
The vulnerable header is X-React-Router-Prerender-Data, a specific JSON object must be passed to it in order for the spoofing to be successful as we will see shortly. Here is the vulnerable code :
To use the header, React-router must be used in Framework mode, and for the attack to be possible the target page must use a loader.
Versions used for our PoC:
routes/ssr).data. In our case the page is called /ssr:We access it by adding the suffix .data and retrieve the data object, needed for the header:
X-React-Router-Prerender-Data header with the previously retrieved object as its value. You can change any value of your data object (do not touch the other values, the latter being necessary for the object to be processed correctly and not throw an error):As you can see, all values have been changed/overwritten by the values provided via the header.
The impact is significant, if a cache system is in place, it is possible to poison a response in which all of the data transmitted via a loader would be altered by an attacker allowing him to take control of the content of the page and modify it as he wishes via a cache-poisoning attack. This can lead to several types of attacks including potential stored XSS depending on the context in which the data is injected and/or how the data is used on the client-side.
React Router allows a DoS via cache poisoning by forcing SPA mode
After some research, it turns out that it is possible to force an application to switch to SPA mode by adding a header to the request. If the application uses SSR and is forced to switch to SPA, this causes an error that completely corrupts the page. If a cache system is in place, this allows the response containing the error to be cached, resulting in a cache poisoning that strongly impacts the availability of the application.
The vulnerable header is X-React-Router-SPA-Mode; adding it to a request sent to a page/endpoint using a loader throws an error. Here is the vulnerable code :
To use the header, React-router must be used in Framework mode, and for the attack to be possible the target page must use a loader.
Versions used for our PoC:
routes/ssr)/ssr in our case) adding the following header:X-React-Router-SPA-Mode: yes
Notice the difference between a request with and without the header;
Normal request
With the header
If a system cache is in place, it is possible to poison the response by completely altering its content (by an error message), strongly impacting its availability, making the latter impractical via a cache-poisoning attack.