CVE-2025-43864 React Router allows a DoS via cache poisoning by forcing SPA mode
Attackers can force SPA mode via headers to corrupt SSR pages and poison caches, causing denial of service in React Router applications.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-43864?
CVE-2025-43864 is a high-severity denial of service vulnerability in remix-run react-router, published on 25 Apr 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
React Router is a router for React. Starting in version 7.2.0 and prior to version 7.5.2, 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. This issue has been patched in version 7.5.2.
Weakness: CWE-755
Which versions are affected by CVE-2025-43864?
2 open source packages ship an affected version, including react-router.
| Package | Affected | Fixed in |
|---|---|---|
react-router npm | From 7.2.0 | 7.5.2 |
react-router npm | From 7.2.0 | 7.5.2 |
How do I fix CVE-2025-43864?
Upgrade react-router to 7.5.2 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-43864 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-43864 exists.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-f46r-rw29-r322.