What’s Vulnerable › Vulnerabilities

CVE-2026-84997: react/http: A malformed HTTP chunked body can lead to a denial-of-service and peg the CPU

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-16 · updated 2026-09-30
• Weakness: CWE-835

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 products

• reactphp http: from 0.6.0, < 1.11.1

References

• https://github.com/reactphp/http/commit/b6d4688790adf3797071fcf88a3fc4225f30486a
• https://github.com/reactphp/http/releases/tag/v1.11.1
• https://github.com/reactphp/http/security/advisories/GHSA-x424-64qh-5j54
• https://github.com/reactphp/http/security/advisories/GHSA-x424-64qh-5j54

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