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High, CVSS 8.6amended

Next.js vulnerable to server-side request forgery in applications using WebSocket upgrades

CVE-2026-44578GHSA-c4j6-fc7j-m34r

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (next 16.2.5, 15.5.16), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm next

    Affected
    >= 13.4.13, < 15.5.16>= 16.0.0, < 16.2.5
    Fixed in
    16.2.5, 15.5.16

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
8.6 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
EPSS
  • CVE-2026-44578: 35.54% estimated exploitation activity in the next 30 days; percentile 98.46 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-c4j6-fc7j-m34r

  2. Revision 1 · created ·

    Published from osv record GHSA-c4j6-fc7j-m34r

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-44578

Advisory: Next.js vulnerable to server-side request forgery in applications using WebSocket upgrades
IDs: CVE-2026-44578, GHSA-c4j6-fc7j-m34r
Record: https://patchnext.com/advisories/cve-2026-44578 (revision 2, source checked 26 Oct 2026, 12:52 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: next 16.2.5, 15.5.16. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm next: affected >= 13.4.13, < 15.5.16; >= 16.0.0, < 16.2.5; fixed in 16.2.5, 15.5.16

## Suggested inspection (read-only)
- `npm ls next --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on next.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-c4j6-fc7j-m34r (OSV record GHSA-c4j6-fc7j-m34r lists affected ranges: npm next >=13.4.13 =16.0.0 <16.2.5 (fixed))
- Verified: https://github.com/advisories/GHSA-c4j6-fc7j-m34r (GitHub-reviewed advisory GHSA-c4j6-fc7j-m34r lists affected ranges: npm next >=13.4.13 =16.0.0 <16.2.5)

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