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Next.js is vulnerable to RCE in React flight protocol

Critical severity GitHub Reviewed Published Dec 3, 2025 in vercel/next.js • Updated Dec 4, 2025

Package

npm next (npm)

Affected versions

>= 14.3.0-canary.77, < 15.0.5
>= 15.2.0-canary.0, < 15.2.6
>= 15.3.0-canary.0, < 15.3.6
>= 15.4.0-canary.0, < 15.4.8
>= 16.0.0-canary.0, < 16.0.7
>= 15.1.0-canary.0, < 15.1.9
>= 15.5.0-canary.0, < 15.5.7

Patched versions

15.0.5
15.2.6
15.3.6
15.4.8
16.0.7
15.1.9
15.5.7

Description

A vulnerability affects certain React packages1 for versions 19.0.0, 19.1.0, 19.1.1, and 19.2.0 and frameworks that use the affected packages, including Next.js 15.x and 16.x using the App Router. The issue is tracked upstream as CVE-2025-55182.

Fixed in:
React: 19.0.1, 19.1.2, 19.2.1
Next.js: 15.0.5, 15.1.9, 15.2.6, 15.3.6, 15.4.8, 15.5.7, 16.0.7

The vulnerability also affects experimental canary releases starting with 14.3.0-canary.77. Users on any of the 14.3 canary builds should either downgrade to a 14.x stable release or 14.3.0-canary.76.

All users of stable 15.x or 16.x Next.js versions should upgrade to a patched, stable version immediately.

1 The affected React packages are:

  • react-server-dom-parcel
  • react-server-dom-turbopack
  • react-server-dom-webpack

References

@aaronbrown-vercel aaronbrown-vercel published to vercel/next.js Dec 3, 2025
Published by the National Vulnerability Database Dec 3, 2025
Published to the GitHub Advisory Database Dec 3, 2025
Reviewed Dec 3, 2025
Last updated Dec 4, 2025

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS score

Weaknesses

Deserialization of Untrusted Data

The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid. Learn more on MITRE.

CVE ID

CVE-2025-66478

GHSA ID

GHSA-9qr9-h5gf-34mp

Source code

Credits

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