Vulnerability · Published Jun 22, 2026 · Assigned by GitHub_M
CVE-2026-54277AIOHTTP: C HTTP Parser Bypasses max_line_size for Fragmented Lines
Medium 6.6
In plain English
A medium-severity resource allocation without limits in aiohttp from aio-libs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | python-aiohttp | 3.8.4-1+deb12u2 | DEBIAN-CVE-2026-54277 |
| Debian:13 | python-aiohttp | no fix listed | DEBIAN-CVE-2026-54277 |
| Debian:14 | python-aiohttp | 3.14.1-1 | DEBIAN-CVE-2026-54277 |
| PyPI | aiohttp | 3.14.1 | PYSEC-2026-2110 |
| PyPI | aiohttp | 3.14.1 | GHSA-63hw-fmq6-xxg2 |
| Ubuntu:25.10 | python-aiohttp | no fix listed | UBUNTU-CVE-2026-54277 |
| Ubuntu:26.10 | python-aiohttp | no fix listed | UBUNTU-CVE-2026-54277 |
Affected products (as reported)
Weakness: CWE-770 · 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