---
id: CVE-2025-53643
aliases:
  - GHSA-9548-qrrj-x5pj
  - PYSEC-2026-1104
title: ' AIOHTTP is vulnerable to HTTP Request/Response Smuggling through incorrect parsing of chunked trailer sections'
summary: ' AIOHTTP is vulnerable to HTTP Request/Response Smuggling through incorrect parsing of chunked trailer sections'
severity: low
vendor: aiohttp
product: aiohttp
ecosystem: pip
affected:
  - aiohttp < 3.12.14
patched:
  - aiohttp 3.12.14
published: '2025-07-14'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:50:26.231846188Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-9548-qrrj-x5pj'
references:
  - url: >-
      https://github.com/aio-libs/aiohttp/security/advisories/GHSA-9548-qrrj-x5pj
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-53643'
  - url: >-
      https://github.com/aio-libs/aiohttp/commit/e8d774f635dc6d1cd3174d0e38891da5de0e2b6a
  - url: 'https://github.com/aio-libs/aiohttp'
tags:
  - osv
  - pip
epss: 0.00312
epssPercentile: 0.24251
ingestedAt: '2026-07-08T18:25:47.749Z'
---

## Overview

### Summary
The Python parser is vulnerable to a request smuggling vulnerability due to not parsing trailer sections of an HTTP request.

### Impact
If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTP_NO_EXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections.

----

Patch: https://github.com/aio-libs/aiohttp/commit/e8d774f635dc6d1cd3174d0e38891da5de0e2b6a

## Affected packages

- `aiohttp < 3.12.14`

## Remediation

Upgrade to a patched release:

- `aiohttp 3.12.14`