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Fencer Vulns
medium 5.9

CVE-2025-30218 json

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

published 2025-04-02 19 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-9629 , GHSA-223j-4rm8-mrmf

cvss
5.9
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

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

Patch / fix

  • npm next 12.3.6, 13.5.10, 14.2.26, 15.2.4
  • vercel next.js 12.3.6, 13.5.10, 14.2.26, 15.2.4

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-30218 updated cvss 3.7

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

  • Red Hat Enterprise Linux 7 firefox Red Hat Enterprise Linux 8 firefox, thunderbird Red Hat Enterprise Linux 9 firefox, dotnet7.0, dotnet-host, firefox-x11, thunderbird, dotnet-sdk-7.0, +9 more Red Hat Enterprise Linux 10 firefox, thunderbird Red Hat Enterprise Linux AI (RHEL AI) rhelai1/ui-rhel9, rhelai1/pathservice-rhel9 Red Hat Trusted Artifact Signer rhtas/rekor-search-ui-rhel9
    +1 more products
    Red Hat streams for Apache Kafka 2 com.github.streamshub-console
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
19 mo ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 1.7 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U
CNA 4.0 1.7 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
npm next
>=12.3.5, <12.3.6
>=13.5.9, <13.5.10
>=14.2.25, <14.2.26
>=15.2.3, <15.2.4
12.3.6
13.5.10
14.2.26
15.2.4

Affected products

  • vercel next.js

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of vercel/next.js published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.