What is CVE-2026-54275?

CVE-2026-54275 is a high-severity vulnerability in Aiohttp, classified under Improper Validation of Certificate with Host Mismatch. CVSS score: 7.5/10. Published 2026-06-22.

How severe is CVE-2026-54275?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Aiohttp

CVE-2026-54275

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.1, the server_hostname TLS SNI check can be bypassed when an existing connection is reused. If an application makes multiple requests to the same…

EPSS: 0.003 (18.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Aiohttp
Aio-libs Aiohttp — versions < 3.14.1

Weakness classification (CWE)

CWE-297 — Improper Validation of Certificate with Host Mismatch

References

security-advisories@github.com (x_refsource_CONFIRM, Third Party Advisory)

Frequently asked questions

What is CVE-2026-54275?: CVE-2026-54275 is a high-severity vulnerability in Aiohttp, classified under Improper Validation of Certificate with Host Mismatch. CVSS score: 7.5/10. Published 2026-06-22.
How severe is CVE-2026-54275?: High severity. CVSS v3 base score is 7.5 out of 10.