CVE-2026-54277

AIOHTTP: C HTTP Parser Bypasses max_line_size for Fragmented Lines

Published Jun 22, 2026 CVSS 4.0 · 6.6 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4876-1 python-aiohttp security update
Github GHSA Github GHSA GHSA-63hw-fmq6-xxg2 aiohttp: C HTTP Parser Bypasses max_line_size for Fragmented Lines
History
Type Values Removed Values Added
Weaknesses CWE-131
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Aio-libs
Aio-libs aiohttp
Vendors & Products Aio-libs
Aio-libs aiohttp
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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jun 23, 2026, 4:10 PM
Reserved
Jun 12, 2026, 5:13 PM
Status
Analyzed
Published
Jun 22, 2026, 6:16 PM
Modified
Oct 25, 2026, 11:10 PM
Severity
Moderate
Public date
Jun 22, 2026, 4:37 PM