VulnerabilityPublished 3 Apr 2024Updated 4 Nov 2025

CVE-2024-2653: amphp/http-client · Excessive Memory Allocation

Affects amphp/http-clientSource CVE Database V5

Not known to be exploited · 83% EPSS · CVSS 8.2 High.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

8.2High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 83.3% chance of exploitation in 30 days – higher than 99% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 3 Apr 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
GitHubamphp/http-client`pkg:github/amphp/http-client`Other threats	Affected =4.0.0-rc10	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Monitor vendor channels closely for official patches or updates addressing CVE-2024-2653 and apply them promptly once available.
In the interim, implement strict HTTP/2 frame size limits at the network perimeter or via reverse proxies to prevent excessive CONTINUATION frame sequences from reaching vulnerable clients.
Employ runtime memory usage monitoring and alerting on services using amphp/http-client to detect abnormal memory consumption patterns indicative of exploitation attempts.
Consider deploying Web Application Firewalls (WAFs) or HTTP/2-aware intrusion prevention systems that can detect and block malformed or suspicious HTTP/2 frames.
Review and restrict exposure of services using the vulnerable library to untrusted networks where possible, reducing the attack surface.
Conduct code audits and testing for similar unbounded buffer issues in other components to prevent analogous vulnerabilities.
Educate development teams on secure handling of protocol frames and memory management best practices to avoid future CWE-789 issues.

Description

amphp/http will collect CONTINUATION frames in an unbounded buffer and will not check a limit until it has received the set END_HEADERS flag, resulting in an OOM crash.

Impact

For European organizations, the primary impact of CVE-2024-2653 is on service availability. Applications and services using the vulnerable amphp/http-client library for HTTP/2 communications may crash due to OOM conditions triggered by maliciously crafted HTTP/2 CONTINUATION frames. This can lead to denial of service, affecting business continuity, customer trust, and potentially causing financial losses. Organizations in sectors such as finance, e-commerce, and public services that rely on asynchronous PHP frameworks and HTTP/2 for performance and scalability are particularly at risk. Additionally, the disruption could be exploited as part of a larger attack chain to weaken defenses or distract security teams. Given the remote exploitability without authentication, attackers can target exposed services directly, increasing the threat surface. The lack of known exploits currently provides a window for proactive defense, but the high CVSS score indicates that exploitation could have severe consequences if weaponized.

CWE-789Memory Allocation with Excessive Size Value (opens in a new tab)
Variant weakness
The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.
Implementation · Architecture and Design
Perform adequate input validation against any value that influences the amount of memory that is allocated. Define an appropriate strategy for handling requests that exceed the limit, and consider supporting a configuration option so that the administrator can extend the amount of memory to be used if necessary.
Operation
Run your program using system-provided resource limits for memory. This might still cause the program to crash or exit, but the impact to the rest of the system will be minimized.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V8.1.4 (opens in a new tab)
V13.4.1 (opens in a new tab)
V11.1.4 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Nov 2025, 18:45 UTC

WeaknessesCWE-789

Technical details

References

Community reviews

Related threats