CVE-2026-54277CWE-770

AIOHTTP: C HTTP Parser Bypasses max_line_size for Fragmented Lines

Medium · published June 22, 2026

CVSS v4.0
6.6
EPSS
1%
Percentile
46.1
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
6.6 · MEDIUM
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
EPSS
0.00563 · 46.1th percentile
Weakness
CWE-770 · Allocation of Resources Without Limits or Throttling
Published
2026-06-22T16:37Z
EPSS history
Timeline
  • 22 JUN 16:37Z
    AIOHTTP: C HTTP Parser Bypasses max_line_size for Fragmented Lines
    cvelistv5