What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-15 · updated 2026-10-16
• Weakness: CWE-770

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.

Affected products

• reactphp http: from 1.0.0, < 1.11.1

References

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

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