Next.js may leak x-middleware-subrequest-id to external hosts
Priority LOW 10CWE-200Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Attack requirements
- Present
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- Low · None · None
- Fix status
- Partial Red Hat: 7 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-200.
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00431 37th percentileScored 2026-11-07
Fix Partial next (npm): 12.3.6, 13.5.10, 14.2.26 +1Red Hat: 7 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| vercel | next.js | = 12.3.5; = 13.5.9; = 14.2.25; = 15.2.3 | — | No fix listed | CNA |
| — | next (npm) | 12.3.5 to before 12.3.6 | 12.3.6 | Patch available | GHSA-223j-4rm8-mrmf |
| — | next (npm) | 13.5.9 to before 13.5.10 | 13.5.10 | Patch available | GHSA-223j-4rm8-mrmf |
| — | next (npm) | 14.2.25 to before 14.2.26 | 14.2.26 | Patch available | GHSA-223j-4rm8-mrmf |
| — | next (npm) | 15.2.3 to before 15.2.4 | 15.2.4 | Patch available | GHSA-223j-4rm8-mrmf |
- next.js Vendorvercel Affected = 12.3.5; = 13.5.9; = 14.2.25; = 15.2.3 Fixed in — No fix listed CNA
- next (npm) Vendor— Affected 12.3.5 to before 12.3.6 Fixed in 12.3.6 Patch available GHSA-223j-4rm8-mrmf
- next (npm) Vendor— Affected 13.5.9 to before 13.5.10 Fixed in 13.5.10 Patch available GHSA-223j-4rm8-mrmf
- next (npm) Vendor— Affected 14.2.25 to before 14.2.26 Fixed in 14.2.26 Patch available GHSA-223j-4rm8-mrmf
- next (npm) Vendor— Affected 15.2.3 to before 15.2.4 Fixed in 15.2.4 Patch available GHSA-223j-4rm8-mrmf
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:vercel:next.js:12.3.5:*:*:*:*:node.js:*:* | 12.3.5 | Vulnerable | vercel |
| cpe:2.3:a:vercel:next.js:13.5.9:*:*:*:*:node.js:*:* | 13.5.9 | Vulnerable | vercel |
| cpe:2.3:a:vercel:next.js:14.2.25:*:*:*:*:node.js:*:* | 14.2.25 | Vulnerable | vercel |
| cpe:2.3:a:vercel:next.js:15.2.3:*:*:*:*:node.js:*:* | 15.2.3 | Vulnerable | vercel |
- cpe:2.3:a:vercel:next.js:12.3.5:*:*:*:*:node.js:*:* Versions 12.3.5 Vulnerable ·vercel
- cpe:2.3:a:vercel:next.js:13.5.9:*:*:*:*:node.js:*:* Versions 13.5.9 Vulnerable ·vercel
- cpe:2.3:a:vercel:next.js:14.2.25:*:*:*:*:node.js:*:* Versions 14.2.25 Vulnerable ·vercel
- cpe:2.3:a:vercel:next.js:15.2.3:*:*:*:*:node.js:*:* Versions 15.2.3 Vulnerable ·vercel
Remediation
- Fix · GHSA-223j-4rm8-mrmf next (npm) Fixed in 12.3.6 Advisory →
- Fix · GHSA-223j-4rm8-mrmf next (npm) Fixed in 13.5.10 Advisory →
- Fix · GHSA-223j-4rm8-mrmf next (npm) Fixed in 14.2.26 Advisory →
- Fix · GHSA-223j-4rm8-mrmf next (npm) Fixed in 15.2.4 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AI (RHEL AI) | Affected | No fix yet: Fix deferred |
| Red Hat Trusted Artifact Signer | Affected | No fix yet: Fix deferred |
| streams for Apache Kafka 2 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2025-30218
- 2026-10-03 Alias added: GHSA-223j-4rm8-mrmf
References
More vercel Next.js vulnerabilities
- TI-2025-34861 Deserialization of untrusted data in Meta react-server-dom-webpack KEVCVSS 3.1CRITICAL 10.0
- TI-2025-21309 Authorization Bypass in Next.js Middleware CVSS 3.1CRITICAL 9.1
- TI-2025-34863 Deserialization of untrusted data in Meta react-server-dom-webpack CVSS 3.1HIGH 7.5
- TI-2024-31371 Cache Poisoning in next.js CVSS 3.1HIGH 7.5
- TI-2023-24914 Next.js before 13.4.20-canary.13 lacks a cache-control header and thus empty prefetch… CVSS 3.1HIGH 7.5
- TI-2026-32490 Next.js: Server-side request forgery in applications using WebSocket upgrades CVSS 3.1HIGH 8.6
Sources
- CVE-2025-30218 · CVE Program
- CVE-2025-30218 · NVD
- FIRST EPSS
- GHSA-223j-4rm8-mrmf · GitHub Advisory Database · CC BY 4.0
- CVE-2025-30218 · Red Hat security data · CC BY 4.0
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