HTTP Response Splitting Affecting py3-aiohttp package, versions <3.13.5-r0


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.06% (20th percentile)

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  • Snyk IDSNYK-ALPINE323-PY3AIOHTTP-16322639
  • published30 Apr 2026
  • disclosed1 Apr 2026

Introduced: 1 Apr 2026

CVE-2026-34520  (opens in a new tab)
CWE-113  (opens in a new tab)

How to fix?

Upgrade Alpine:3.23 py3-aiohttp to version 3.13.5-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream py3-aiohttp package and not the py3-aiohttp package as distributed by Alpine. See How to fix? for Alpine:3.23 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1