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Vulnerabilities

Vulnerability · CVE-2026-104827

react/http is an event-driven, streaming HTTP client and server implementation for ReactPHP.

Published Oct 15, 2026 · catalog updated Oct 15, 2026 · react/http is an event-driven,

Check if you run it

No confirmed exploitation is on record for CVE-2026-104827. EPSS is 0.43%. Act only if a listed version of react/http is an event-driven, is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (react/http is an event-driven,).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.43%
Remediation
Advisory link
Affected products
Packagist react/http · composer react

### Summary and its lower-level HTTP stack impose no limit on the size of a response's header section while it is being received. appends every incoming byte to an internal buffer and only scans that buffer for the (or ) 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 is exhausted and the process crashes. This is an unauthenticated, network-reachable denial of service against any application that uses as a client to fetch untrusted or attacker-influenced URLs, including via redirects. ### Details is bound directly to the underlying connection's 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 monotonically for as long as the peer keeps sending. The codebase already applies this class of limit elsewhere, but not symmetrically. caps incoming **request** headers when acting as a server, and caps the response **body**, but only once the header section has already been parsed into a . Response header reception was the one stage with no limit at all. ### PoC An HTTP server that sends a valid status line and a partial header, then streams indefinitely without ever terminating the header section: A client fetching it, with : Client memory grows steadily until the process dies with inside . ### Impact Remotely triggerable, unauthenticated denial of service against any process using to fetch from an attacker-controlled, compromised or otherwise untrusted endpoint, including one reached through a redirect. No user interaction and no special privileges are required. Because there is no upper bound on the header buffer, a single cheap connection can drive memory arbitrarily high and crash the process, taking down whatever event loop or worker it was running. Confidentiality and integrity are unaffected; availabili

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Packagist react/http1.0.0 → 1.11.1
  • composer reactversion unspecified

How to fix CVE-2026-104827

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-104827. EPSS is 0.43%. Act only if a listed version of react/http is an event-driven, is installed.

Which versions are affected?

Compare what you have installed with 1.0.0 → 1.11.1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-770: Allocation of Resources Without Limits or Throttling. EPSS 0.43%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 15, 2026 · NIST NVD

    Detected

    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 d

  2. Oct 15, 2026 · GitHub Advisory Database

    Fix available

    react/http fixed in 1.11.1

  3. Oct 15, 2026 · GitHub Advisory Database

    Fix available

    react/http fixed in 1.11.1

  4. Oct 15, 2026 · GitHub Advisory Database

    Updated

    ### Summary and its lower-level HTTP stack impose no limit on the size of a response's header section while it is being received. appends every incoming byte to an internal buffer and only scans that buffer for the (or ) 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 is exhausted

Sources

  • CVE.orgVulnerability recordCVE-2026-104827

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-104827

    30-day exploitation probability 0.4%

    first.org
  • GitHub Advisory DatabasePackage advisoryGHSA-g4f2-2pf3-2pwj

    GitHub Advisory Database record mirrored by OSV.

    github.com
  • GitLab Advisory DatabasePackage advisoryCVE-2026-104827

    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

    advisories.gitlab.com
  • NIST NVDVulnerability recordCVE-2026-104827

    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 ca

    nvd.nist.gov
  • OpenSSF OSV / OSV ScannerPackage advisoryGHSA-g4f2-2pf3-2pwj

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

    osv.dev

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.