aiohttp: C HTTP Parser Bypasses max_line_size for Fragmented Lines (CVE-2026-54277) | HOL Guard CVE

High · CVSS 7.5CVE-2026-54277GHSA-63HW-FMQ6-XXG2

aiohttp: C HTTP Parser Bypasses max_line_size for Fragmented Lines

Answer in brief

CVE-2026-54277 records a High severity (CVSS 7.5) vulnerability in aiohttp: C HTTP Parser Bypasses max_line_size for Fragmented Lines. The current sources do not mark it as known exploited. The current feed maps aiohttp (pip), aiohttp (pypi). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jun 15, 2026Updated Sep 10, 2026Source checked Sep 18, 2026First seen by HOL Jun 19, 2026Material review Sep 10, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps aiohttp (pip), aiohttp (pypi). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
aiohttppip	<=3.14.0	3.14.1
aiohttppypi	>=0 <3.14.1	3.14.1

Recommended response

Check inventory. Check lockfiles and deployed manifests for aiohttp, aiohttp.
Review the reported fix. Update aiohttp to 3.14.1; aiohttp to 3.14.1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Jun 15, 2026
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Jun 19, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.