AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.1, it is possible to bypass the max_line_size check in parts of an HTTP request in the C parser. If using the optimised C parser (the default in pre-built wheels), then an attacker may be able to send oversized lines through the HTTP parser and use an excessive amount of memory, potentially leading to DoS. This vulnerability is fixed in 3.14.1.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
aio-libs aiohttp affected
Version Status Constraints
< 3.14.1 affected —

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Project Subscriptions

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-63hw-fmq6-xxg2 aiohttp: C HTTP Parser Bypasses max_line_size for Fragmented Lines
Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/aio-libs/aiohttp/commit/5ab61bb4cd88f19b712f12c7c9295fe262bf804d cve-icon
https://github.com/aio-libs/aiohttp/security/advisories/GHSA-63hw-fmq6-xxg2 cve-icon
History

Mon, 22 Jun 2026 17:30:00 +0000

Type Values Removed Values Added
Description AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.1, it is possible to bypass the max_line_size check in parts of an HTTP request in the C parser. If using the optimised C parser (the default in pre-built wheels), then an attacker may be able to send oversized lines through the HTTP parser and use an excessive amount of memory, potentially leading to DoS. This vulnerability is fixed in 3.14.1.
Title AIOHTTP: C HTTP Parser Bypasses max_line_size for Fragmented Lines
Weaknesses CWE-770
References
Metrics cvssV4_0

{'score': 6.6, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-06-22T16:37:28.532Z

Reserved: 2026-06-12T17:13:32.280Z

Link: CVE-2026-54277

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

Updated: 2026-06-22T18:45:04Z

Weaknesses