CVE-2025-30218 - CVE House
Back to Database
Status published Low CVE-2025-30218

Next.js may leak x-middleware-subrequest-id to external hosts

Vulnerability Description

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 vulnerability is fixed in 12.3.6, 13.5.10, 14.2.26, and 15.2.4.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

THREAT MONITOR

Am I Vulnerable?

Launch our assessment wizard to check if your infrastructure is exposed to • CVE-2025-30218

Credits & Attribution

No credits recorded in the NVD database.

References

More from vercel

View All →
CVE-2025-7074
vercel hyper rimraf-standalone.js ignoreMap redos
Medium 5.3
CVE-2025-59472
A denial of service vulnerability exists in Next.js versions with...
Medium 5.9
CVE-2025-59471
A denial of service vulnerability exists in self-hosted Next.js applications...
Medium 5.9
CVE-2025-57822
Next.js Improper Middleware Redirect Handling Leads to SSRF
Medium 6.5
CVE-2025-57752
Next.js Affected by Cache Key Confusion for Image Optimization API Routes
Medium 6.2

Affected Vendor

Affected Software

next.js
Vulnerable Versions:
= 12.3.5, = 13.5.9, = 14.2.25, = 15.2.3

Timeline

Official Publish: April 2nd, 2025
Last Modified: October 13th, 2025
Added to House: July 22nd, 2026

CVSS Vectors

Weaknesses (CWE)

CWE-200

MITRE ATT&CK TTPs

T1213 Data from Information Repositories
Collection
T1005 Data from Local System
Collection
T1552 Unsecured Credentials
Credential Access
T1041 Exfiltration Over C2 Channel
Exfiltration