CVE-2026-34525CWE-20CWE-444

AIOHTTP: Duplicate Host header accepted

Medium · published April 1, 2026

CVSS v4.0
6.3
EPSS
0%
Percentile
32.2
In the wild
Unconfirmed
What it is

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, multiple Host headers were allowed in aiohttp. This issue has been patched in version 3.13.4.

The record
Technical detail
CVSS v4.0
6.3 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N
EPSS
0.00393 · 32.2th percentile
Weaknesses
CWE-20 · Improper Input Validation; CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Published
2026-04-01T20:28Z
EPSS history
Timeline
  • 01 APR 20:28Z
    AIOHTTP: Duplicate Host header accepted
    cvelistv5