react/http: Unbounded HTTP Client Response Header Buffering Leads to Memory Exhaustion DoS

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-104827: 0.52% estimated exploitation activity in the next 30 days; percentile 44.07 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary React\Http\Browser and its lower-level HTTP stack impose no limit on the size of a response's header section while it is being received. ClientRequestStream::handleData() appends every incoming byte to an internal buffer and only scans that buffer for the \r\n\r\n (or \n\n) terminator, without ever checking its length. A remote server that withholds the terminator and keeps streaming can grow the client's memory without bound until PHP's memorylimit is exhausted and the process crashes. This is an unauthenticated, network-reachable denial of service against any application that uses react/http as a client to fetch untrusted or attacker-influenced URLs, including via redirects. Details ClientRequestStream::handleData() is bound directly to the underlying connection's data event, so every byte the peer sends is appended with no size check: The only exit from the buffering state is finding the header terminator or a connection close, so until it arrives the buffer grows…

Published by the source

15 Oct 2026, 20:09 UTC

Last modified by the source

15 Oct 2026, 20:30 UTC

Source last checked

26 Oct 2026, 14:53 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-g4f2-2pf3-2pwj

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-g4f2-2pf3-2pwj

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-104827

Advisory: react/http: Unbounded HTTP Client Response Header Buffering Leads to Memory Exhaustion DoS
IDs: CVE-2026-104827, GHSA-g4f2-2pf3-2pwj
Record: https://patchnext.com/advisories/cve-2026-104827 (revision 2, source checked 26 Oct 2026, 14:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: react/http 1.11.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist react/http: affected >= 1.0.0, <= 1.11.0; fixed in 1.11.1

## Suggested inspection (read-only)
- Packagist react/http: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on react/http.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-g4f2-2pf3-2pwj (OSV record GHSA-g4f2-2pf3-2pwj lists affected ranges: Packagist react/http >=1.0.0 <1.11.1 (fixed))
- Verified: https://github.com/advisories/GHSA-g4f2-2pf3-2pwj (GitHub-reviewed advisory GHSA-g4f2-2pf3-2pwj lists affected ranges: Packagist react/http >=1.0.0 <=1.11.0)

Commands are suggestions: review each one before running it.