# CVE-2025-31137: Remix and React Router allow URL manipulation via Host / X-Forwarded-Host headers

- Exploited (CISA KEV): no
- Published: 2025-04-01
- CVSS: 7.5 HIGH (v3.0)
- EPSS: 1.2% (68th percentile)
- CWE: CWE-444

React Router is a multi-strategy router for React bridging the gap from React 18 to React 19. There is a vulnerability in Remix/React Router that affects all Remix 2 and React Router 7 consumers using the Express adapter. Basically, this vulnerability allows anyone to spoof the URL used in an incoming Request by putting a URL pathname in the port section of a URL that is part of a Host or X-Forwarded-Host header sent to a Remix/React Router request handler. This issue has been patched and released in Remix 2.16.3 and React Router 7.4.1.

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

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | No public claim | — | — |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | No public claim | — | — |
| Fastly | Before feed history | — | — |
| F5 | Rule published | 2025-05-22 | 51 |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### F5

- 2025-05-22 · new · rule 200013115
  > Added: signature 200013115 "React Router URL Manipulation (1)" (Authentication/Authorization Attacks, risk Medium), systems: JavaScript, ReactJS. References: CVE-2025-31137.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog
- 2025-05-22 · new · rule 200013116
  > Added: signature 200013116 "React Router URL Manipulation (2)" (Authentication/Authorization Attacks, risk Medium), systems: JavaScript, ReactJS. References: CVE-2025-31137.
  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-2025-31137 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2025-31137