CVE-2024-2653Network attack vector

Unauthenticated crash via unbounded CONTINUATION frame buffering

Published Apr 3, 2024 · Updated Nov 4, 2025

Resource exhaustion in AMPHP HTTP and HTTP Client affected releases allows remote attackers to crash HTTP/2 applications. The HTTP/2 parser appends each CONTINUATION frame to headerBuffer but delays the configured header-size check until END_HEADERS, permitting unbounded memory growth. An unauthenticated peer that can exchange HTTP/2 traffic with a consuming client or server can exhaust PHP process memory and interrupt that application.

CVSS severity8.2
High
EPSS probability83.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in AMPHP HTTP and HTTP Client affected releases allows remote attackers to crash HTTP/2 applications. The HTTP/2 parser appends each CONTINUATION frame to headerBuffer but delays the configured header-size check until END_HEADERS, permitting unbounded memory growth. An unauthenticated peer that can exchange HTTP/2 traffic with a consuming client or server can exhaust PHP process memory and interrupt that application.

The record

CVE
CVE-2024-2653
Published
Apr 3, 2024
Updated
Nov 4, 2025
Vendor
AMPHP
Product
AMPHP HTTP Client
Classifications
CWE-789, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 3, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=v4.0.0-rc10 <=4.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

AMPHP · AMPHP HTTP Clientversion=v4.0.0-rc10 <=4.0.0
AMPHP · AMPHP HTTPversion=2.0.0-beta.1 <=2.1.0; version=2.0.0-beta1 <=2.1.0; version=v1.6.0-rc1 <=1.7.2

Published CVSS scores

8.2CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-789Memory Allocation with Excessive Size Value
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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