CVE-2026-48809Network attack vector

Service interruption via unchecked message allocation

Published Aug 11, 2026 · Updated Aug 11, 2026

Resource exhaustion in python-engineio 4.13.4 and earlier allows remote attackers to interrupt service via oversized Engine.IO messages. The ASGI translate_request path reads long-polling POST bodies before client and size checks, while Aiohttp WebSocket handling lacks an enforced message limit. Unauthenticated exposure requires an affected server and transport combination; repeated oversized input consumes process memory until service fails.

CVSS severity7.5
High
EPSS probability0.28%
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 python-engineio 4.13.4 and earlier allows remote attackers to interrupt service via oversized Engine.IO messages. The ASGI translate_request path reads long-polling POST bodies before client and size checks, while Aiohttp WebSocket handling lacks an enforced message limit. Unauthenticated exposure requires an affected server and transport combination; repeated oversized input consumes process memory until service fails.

The record

CVE
CVE-2026-48809
Published
Aug 11, 2026
Updated
Aug 11, 2026
Vendor
Miguel Grinberg
Product
python-engineio
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 11, 2026Record 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=< 4.13.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Miguel Grinberg · python-engineioversion=< 4.13.2

Published CVSS scores

7.5GitHubCVSS: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.

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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-770Allocation of Resources Without Limits or Throttling
T1499.004Endpoint Denial of Service: Application 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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