Next.js CVE-2026-44578
HIGH
GHSA-c4j6-fc7j-m34r
CVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Lifecycle Timeline
3Blast Radius
ecosystem impact- 21 npm packages depend on next (21 direct, 0 indirect)
Ecosystem-wide dependent count for version 13.4.13.
DescriptionNVD
Impact
Self-hosted applications using the built-in Node.js server can be vulnerable to server-side request forgery through crafted WebSocket upgrade requests. An attacker can cause the server to proxy requests to arbitrary internal or external destinations, which may expose internal services or cloud metadata endpoints. Vercel-hosted deployments are not affected.
Fix
We now apply the same safety checks to WebSocket upgrade handling that already existed for normal HTTP requests, so upgrade requests are only proxied when routing has explicitly marked them as safe external rewrites.
Workarounds
If you cannot upgrade immediately, do not expose the origin server directly to untrusted networks. If WebSocket upgrades are not required, block them at your reverse proxy or load balancer, and restrict origin egress to internal networks and metadata services where possible.
AnalysisAI
Server-side request forgery in Next.js allows remote unauthenticated attackers to proxy requests to arbitrary internal or external destinations through crafted WebSocket upgrade requests in self-hosted applications using the built-in Node.js server. Attackers can access internal services and cloud metadata endpoints (AWS, GCP, Azure instance metadata) without authentication. …
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RemediationAI
Within 24 hours: Identify all self-hosted Next.js deployments and confirm running versions against affected ranges (13.4.13-15.5.15, 16.0.0-16.2.4). Within 7 days: Upgrade to Next.js 15.5.16 or 16.2.5 depending on current major version; verify no Vercel-hosted instances are misconfigured as self-hosted. …
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External POC / Exploit Code
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