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Exposure of Sensitive Information to an Unauthorized Actor

CVE-2025-30218

Low
1.7/10

Summary

Next.js is a React framework for building full-stack web applications. To mitigate CVE-2025-29927, Next.js validated the "x-middleware-subrequest-id" which persisted across multiple incoming requests. However, this subrequest `ID` is sent to all requests, even if the destination is not the same host as the Next.js application. Initiating a fetch request to a third-party within Middleware will send the "x-middleware-subrequest-id" to that third party. This issue affects versions 12.3.5, 13.5.9, 14.2.25, 15.2.3 and 15.3.0-canary.12 through 15.3.0-canary.20.

  • HIGH
  • NETWORK
  • NONE
  • NONE

CWE-200 - Information Exposure

An information exposure vulnerability is categorized as an information flow (IF) weakness, which can potentially allow unauthorized access to otherwise classified information in the application, such as confidential personal information (demographics, financials, health records, etc.), business secrets, and the application's internal environment.

References

Advisory Timeline

  • Published