---
id: CVE-2026-54277
aliases:
  - GHSA-63hw-fmq6-xxg2
  - PYSEC-2026-2110
title: 'aiohttp: C HTTP Parser Bypasses max_line_size for Fragmented Lines'
summary: 'aiohttp: C HTTP Parser Bypasses max_line_size for Fragmented Lines'
severity: medium
vendor: aiohttp
product: aiohttp
ecosystem: pip
affected:
  - aiohttp < 3.14.1
patched:
  - aiohttp 3.14.1
published: '2026-06-15'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:50:48.460120366Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-63hw-fmq6-xxg2'
references:
  - url: >-
      https://github.com/aio-libs/aiohttp/security/advisories/GHSA-63hw-fmq6-xxg2
  - url: >-
      https://github.com/aio-libs/aiohttp/commit/5ab61bb4cd88f19b712f12c7c9295fe262bf804d
  - url: 'https://github.com/aio-libs/aiohttp'
  - url: 'https://github.com/advisories/GHSA-63hw-fmq6-xxg2'
tags:
  - osv
  - pip
  - ghsa
epss: 0.00563
epssPercentile: 0.44573
cwe:
  - CWE-770
ingestedAt: '2026-07-07T15:41:58.690Z'
---

## Overview

### Summary

It is possible to bypass the max_line_size check in parts of an HTTP request in the C parser.

### Impact

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.

-----

Patch: https://github.com/aio-libs/aiohttp/commit/5ab61bb4cd88f19b712f12c7c9295fe262bf804d

## Affected packages

- `aiohttp < 3.14.1`

## Remediation

Upgrade to a patched release:

- `aiohttp 3.14.1`