CVE-2025-69224Network attack vector

Request smuggling via Unicode-folded HTTP headers

Published Jan 5, 2026 · Updated Jan 5, 2026

HTTP request smuggling in aio-libs aiohttp before 3.13.3 allows remote attackers to bypass proxy or firewall protections. The pure-Python HTTP parser lowercases non-ASCII Transfer-Encoding, Upgrade, and Content-Encoding values before comparing them with ASCII protocol tokens. Exposure requires absent C extensions or AIOHTTP_NO_EXTENSIONS, and the resulting parser discrepancy permits intermediary protection bypass.

CVSS severity6.3
Medium
EPSS probability0.24%
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 aio-libs aiohttp before 3.13.3 allows remote attackers to bypass proxy or firewall protections. The pure-Python HTTP parser lowercases non-ASCII Transfer-Encoding, Upgrade, and Content-Encoding values before comparing them with ASCII protocol tokens. Exposure requires absent C extensions or AIOHTTP_NO_EXTENSIONS, and the resulting parser discrepancy permits intermediary protection bypass.

The record

CVE
CVE-2025-69224
Published
Jan 5, 2026
Updated
Jan 5, 2026
Vendor
aio-libs
Product
aiohttp
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 5, 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=< 3.13.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

aio-libs · aiohttpversion=< 3.13.3

Published CVSS scores

6.3GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A: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.

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

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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