Vulnerability · Published Sep 16, 2026 · Assigned by GitHub_M
CVE-2026-84997react/http: A malformed HTTP chunked body can lead to a denial-of-service and peg the CPU
High 7.5
In plain English
A high-severity infinite loop in http from reactphp. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 52% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
react/http is an event-driven, streaming HTTP client and server implementation for ReactPHP. From 0.6.0 until 1.11.1, React\Http\Io\ChunkedDecoder could enter an infinite loop while processing a malformed Transfer-Encoding: chunked body because handleData required its buffer to shrink on every iteration. An incomplete terminal-chunk trailer without CRLF left the buffer unchanged after strpos returned false, and exactly two non-CRLF bytes after a completed non-terminal chunk bypassed both the error and wait guards. The affected decoder processes request bodies for React\Http\HttpServer and response bodies for React\Http\Browser, allowing a malicious client to freeze a server or a malicious or compromised server to freeze a client. A reverse proxy that normalizes inbound requests may protect the server direction but does not protect outbound Browser requests. This issue is fixed in version 1.11.1.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Packagist | react/http | 1.11.1 | GHSA-x424-64qh-5j54 |
Affected products (as reported)
Weakness: CWE-835 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/reactphp/http/security/advisories/GHSA-x424-64qh-5j54 x_refsource_CONFIRM
- https://github.com/reactphp/http/commit/b6d4688790adf3797071fcf88a3fc4225f30486a x_refsource_MISC
- https://github.com/reactphp/http/releases/tag/v1.11.1 x_refsource_MISC