CVE-2026-23869

Impact

A denial of service vulnerability exists in React Server Components, affecting the following packages: react-server-dom-parcel, react-server-dom-turbopack, react-server-dom-webpack versions 19.0.0, 19.1.0 and 19.2.0. The vulnerability is triggered by sending specially crafted HTTP requests to Server Function endpoints.

The payload of the HTTP request causes excessive CPU usage for up to a minute ending in a thrown error that is catchable.

We recommend updating immediately.

The vulnerability exists in versions 19.0.0 through 19.0.4, 19.1.0 through 19.1.5, and 19.2.0 through 19.2.4 of:

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

Patches

Fixes were back ported to versions 19.0.5, 19.1.6, and 19.2.5.

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.