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Facebook React has a Denial of Service Vulnerability in React Server Components

High severity GitHub Reviewed Published May 6, 2026 in react/react • Updated May 11, 2026

Package

npm react-server-dom-parcel (npm)

Affected versions

>= 19.0.0, < 19.0.6
>= 19.1.0, < 19.1.7
>= 19.2.0, < 19.2.6

Patched versions

19.0.6
19.1.7
19.2.6
npm react-server-dom-turbopack (npm)
>= 19.0.0, < 19.0.6
>= 19.1.0, < 19.1.7
>= 19.2.0, < 19.2.6
19.0.6
19.1.7
19.2.6
npm react-server-dom-webpack (npm)
>= 19.0.0, < 19.0.6
>= 19.1.0, < 19.1.7
>= 19.2.0, < 19.2.6
19.0.6
19.1.7
19.2.6

Description

Impact

A denial of service vulnerability could be triggered by sending specially crafted HTTP requests to server function endpoints, this could lead to out-of-memory exceptions or excessive CPU usage.

We recommend updating immediately.

The vulnerability exists in versions 19.0.0 through 19.0.5, 19.1.0 through 19.1.6, and 19.2.0 through 19.2.5 of:

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

Patches

Fixes were back ported to versions 19.0.6, 19.1.7, and 19.2.6.

If you are using any of the above packages please upgrade to any of the fixed versions immediately.

If your app’s React code does not use a server, your app is not affected by this vulnerability. If your app does not use a framework, bundler, or bundler plugin that supports React Server Components, your app is not affected by this vulnerability.

References
See the blog post for more information and upgrade instructions.

References

@zpao zpao published to react/react May 6, 2026
Published by the National Vulnerability Database May 6, 2026
Published to the GitHub Advisory Database May 11, 2026
Reviewed May 11, 2026
Last updated May 11, 2026

Severity

High

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
Unchanged
Confidentiality
None
Integrity
None
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:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(73rd percentile)

Weaknesses

Uncontrolled Resource Consumption

The product does not properly control the allocation and maintenance of a limited resource. Learn more on MITRE.

Allocation of Resources Without Limits or Throttling

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. Learn more on MITRE.

CVE ID

CVE-2026-23870

GHSA ID

GHSA-rv78-f8rc-xrxh

Source code

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