---
schema_version: '1.0'
id: security-20260714-4bc02e
url: https://osv.dev/vulnerability/PYSEC-2026-2102
url_hash: 4bc02e56f094e6a1f5680933a3630b03716694a638a8f3c39334b428b6d5bbf5
canonical_url: https://osv.dev/vulnerability/PYSEC-2026-2102
source: osv:pypa
category: security/library
category_raw: cve/library
region: null
tags:
- cve
- CVE-2026-34520
- PYSEC-2026-2102
- severity:CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- aiohttp
- PyPI
lang: en
published_at: '2026-04-01T21:17:00Z'
fetched_at: '2026-07-14T06:42:23Z'
updated_at: '2026-07-14T06:42:55Z'
status: published
content_hash: 3103ac224e2f0cc3c7e71c9bac2728d5b7f360bd2d7a278ee8d125c59a941914
license_note: full
summary: AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python.
  Prior to version 3.13.4, the C parser (the default for most installs) accepted null
  bytes and control characters in response headers. This issue has been patched in
  version 3.13.4.
summary_source: rss
summary_en: AIOHTTP is an asynchronous HTTP client/server framework for asyncio and
  Python. Prior to version 3.13.4, the C parser (the default for most installs) accepted
  null bytes and control characters in response headers. This issue has been patched
  in version 3.13.4.
entities: []
key_facts: []
related: []
related_auto: []
title: CVE-2026-34520 — aiohttp
---

# CVE-2026-34520 — aiohttp

## TL;DR
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, the C parser (the default for most installs) accepted null bytes and control characters in response headers. This issue has been patched in version 3.13.4.

## Key Points
- cve / CVE-2026-34520 / PYSEC-2026-2102 / severity:CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X / aiohttp / PyPI

## Details
**Severity:** CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
**Advisory:** PYSEC-2026-2102 (CVE-2026-34520)

**Affected (your watchlist):**
- `PyPI:aiohttp` 3.13.3 → fixed in 3.13.4 [docker/docker-strands]

**Details:**
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, the C parser (the default for most installs) accepted null bytes and control characters in response headers. This issue has been patched in version 3.13.4.

**References:**
- https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4
- https://github.com/aio-libs/aiohttp/commit/9370b9714a7a56003cacd31a9b4ae16eab109ba4
- https://github.com/aio-libs/aiohttp/security/advisories/GHSA-63hf-3vf5-4wqf

_Data: OSV.dev (upstream: pypa) — https://osv.dev/vulnerability/PYSEC-2026-2102_

## Source
元記事: [CVE-2026-34520 — aiohttp](https://osv.dev/vulnerability/PYSEC-2026-2102) — published 2026-04-01T21:17:00Z