CVE-2026-69243Public exploitNetwork attack vector

Unauthenticated request smuggling via premature WebSocket upgrade

Published Aug 3, 2026 · Updated Aug 3, 2026

HTTP request smuggling in aiohttp before 3.14.2 allows remote attackers to bypass intermediary routing via WebSocket upgrade requests. The Python and C HTTP parsers switch protocols when upgrade headers are parsed instead of waiting until the declared request body is consumed, so trailing body bytes become pipelined data. Exploitation requires server-side aiohttp behind a proxy that forwards upgrade headers and an endpoint that rejects the upgrade; a smuggled request can bypass edge access controls.

CVSS severity6.3
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP request smuggling in aiohttp before 3.14.2 allows remote attackers to bypass intermediary routing via WebSocket upgrade requests. The Python and C HTTP parsers switch protocols when upgrade headers are parsed instead of waiting until the declared request body is consumed, so trailing body bytes become pipelined data. Exploitation requires server-side aiohttp behind a proxy that forwards upgrade headers and an endpoint that rejects the upgrade; a smuggled request can bypass edge access controls.

The record

CVE
CVE-2026-69243
Published
Aug 3, 2026
Updated
Aug 3, 2026
Vendor
aio-libs
Product
aiohttp
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=< 3.14.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

aio-libs · aiohttpversion=< 3.14.2

Published CVSS scores

6.3GitHub, Inc.CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

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 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 exploitPublished

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1190Exploit Public-Facing Application

Public exploit references

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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