---
id: CVE-2026-34513
aliases:
  - GHSA-hcc4-c3v8-rx92
  - PYSEC-2026-2095
title: >-
  AIOHTTP Affected by Denial of Service (DoS) via Unbounded DNS Cache in
  TCPConnector
summary: >-
  AIOHTTP Affected by Denial of Service (DoS) via Unbounded DNS Cache in
  TCPConnector
severity: low
vendor: aiohttp
product: aiohttp
ecosystem: pip
affected:
  - aiohttp < 3.13.4
patched:
  - aiohttp 3.13.4
published: '2026-04-01'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:51:02.067006429Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-hcc4-c3v8-rx92'
references:
  - url: >-
      https://github.com/aio-libs/aiohttp/security/advisories/GHSA-hcc4-c3v8-rx92
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-34513'
  - url: >-
      https://github.com/aio-libs/aiohttp/commit/c4d77c3533122be353b8afca8e8675e3b4cbda98
  - url: 'https://github.com/aio-libs/aiohttp'
  - url: 'https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4'
tags:
  - osv
  - pip
epss: 0.00609
epssPercentile: 0.46854
ingestedAt: '2026-07-13T18:57:59.110Z'
---

## Overview

### Summary

An unbounded DNS cache could result in excessive memory usage possibly resulting in a DoS situation.

### Impact

If an application makes requests to a very large number of hosts, this could cause the DNS cache to continue growing and slowly use excessive amounts of memory.

-----

Patch: https://github.com/aio-libs/aiohttp/commit/c4d77c3533122be353b8afca8e8675e3b4cbda98

## Affected packages

- `aiohttp < 3.13.4`

## Remediation

Upgrade to a patched release:

- `aiohttp 3.13.4`