# CVE-2025-43864: React Router allows a DoS via cache poisoning by forcing SPA mode

- Exploited (CISA KEV): no
- Published: 2025-04-25
- CVSS: 7.5 HIGH (v3.1)
- EPSS: 20.5% (98th percentile)
- CWE: CWE-755

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.

## Edge WAF coverage (claimed by vendors, not measured)

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Blocks by default | 2025-04-26 | 1 |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | No public claim | — | — |
| Fastly | Before feed history | — | — |
| F5 | Rule published | 2025-05-22 | 27 |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### Cloudflare

- 2025-04-26 · new · rule 54ea354d7f2d43c69b238d1419fcc883 · default Block
  > React.js - Router and Remix Vulnerability - CVE:CVE-2025-43864, CVE:CVE-2025-43865. Previous action: Block. New action: Block. This is a New Detection
  Source: https://developers.cloudflare.com/changelog/post/2025-04-26-emergency-waf-release/

### F5

- 2025-05-22 · new · rule 200012093
  > Added: signature 200012093 "React Router SPA Mode DoS" (Denial of Service, risk High), systems: Java Servlets/JSP, ReactJS. References: CVE-2025-43864.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog

"No public claim" means no vendor statement names this CVE; "Before feed history" means the CVE is older than the vendor feed. In both cases generic rules may still block it.

HTML: https://cve.vigilbase.com/cve/CVE-2025-43864 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2025-43864