Vulnerability · Published Jun 22, 2026 · Assigned by GitHub_M

CVE-2026-54275AIOHTTP: TLS Server Hostname Override Is Ignored When Reusing HTTPS Connections

Low 2.7

In plain English

A low-severity security flaw in aiohttp from aio-libs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)2.7Low

Exploit odds (30 days)0.5%top 59.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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 domain, but with different per-request server_hostname parameters, then the later calls may succeed by reusing the existing connection when they should have been rejected due to the TLS SNI check. This vulnerability is fixed in 3.14.1.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:13	python-aiohttp	no fix listed	DEBIAN-CVE-2026-54275
Debian:14	python-aiohttp	3.14.1-1	DEBIAN-CVE-2026-54275
PyPI	aiohttp	3.14.1	GHSA-4m7w-qmgq-4wj5
PyPI	aiohttp	3.14.1	PYSEC-2026-237
Ubuntu:25.10	python-aiohttp	no fix listed	UBUNTU-CVE-2026-54275
Ubuntu:26.10	python-aiohttp	no fix listed	UBUNTU-CVE-2026-54275

Affected products (as reported)

Vendor	Product	Versions
aio-libs	aiohttp	< 3.14.1

Weakness: CWE-297 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U

References

https://github.com/aio-libs/aiohttp/security/advisories/GHSA-4m7w-qmgq-4wj5 x_refsource_CONFIRM