CVE-2024-30251Network attack vector

Unauthenticated service hang via multipart parser loop

Published May 2, 2024 · Updated Nov 3, 2025

Denial of service in aiohttp before 3.9.4 allows remote attackers to hang server applications via a malformed multipart POST request. BodyPartReader._read_chunk_from_length() fails to mark the part complete when the content stream reaches EOF, so repeated reads return no data without ending the loop. Any unauthenticated remote client that can reach a server-side multipart endpoint can hang the application's request processing with one malformed request.

CVSS severity7.5
High
EPSS probability1.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in aiohttp before 3.9.4 allows remote attackers to hang server applications via a malformed multipart POST request. BodyPartReader._read_chunk_from_length() fails to mark the part complete when the content stream reaches EOF, so repeated reads return no data without ending the loop. Any unauthenticated remote client that can reach a server-side multipart endpoint can hang the application's request processing with one malformed request.

The record

CVE
CVE-2024-30251
Published
May 2, 2024
Updated
Nov 3, 2025
Vendor
aio-libs
Product
aiohttp
Classifications
CWE-835, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 2, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 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=< 3.9.4
  2. Affected versionversion=- <3.9.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

aio-libs · aiohttpversion=< 3.9.4; version=- <3.9.4

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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