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EUVD-2026-369545

fkie_cve-2026-84997

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.

GHSA-x424-64qh-5j54 — react/http: A malformed HTTP chunked body can lead to a denial-of-service and peg the CPU

Affected: Packagist: react/http

### Summary

A malformed HTTP message using `Transfer-Encoding: chunked` can drive `React\Http\Io\ChunkedDecoder` into an infinite loop, pegging a CPU core and freezing the event loop. Because ReactPHP is single-threaded, one such message stalls the entire process for every client until it is killed.

Both directions are affected. `ChunkedDecoder` decodes chunked **request** bodies for `React\Http\HttpServer` and chunked **response** bodies for `React\Http\Browser`, so a server can be attacked by a malicious client and a client can be attacked by a malicious or compromised server.

### Details

`ChunkedDecoder::handleData()` loops `while ($this->buffer !== '')` and relies on the buffer shrinking each iteration. Two states leave the buffer unchanged while the loop condition stays true.

**Terminal-chunk trailer.** After the terminating `0` chunk, any remaining buffer is treated as trailer data to skip:

```php } elseif ($this->chunkSize === 0) { $this->buffer = (string)\substr($this->buffer, $positionCrlf); } ```

When the trailer holds no CRLF yet, `strpos()` returns `false`, PHP coerces that to `0` in `substr()`, and the buffer is never advanced. Neither the error guard (which requires a non-zero chunk size) nor the wait guard (which requires fewer than two bytes remaining) can fire, so the loop re-enters with identical state.

**Off-by-one after a completed chunk.** Once a non-terminal chunk has been fully transferred, the "chunk does not end with a CRLF" error guard r…