High severity · published Jun 22, 2026
CVE-2026-54275
AIOHTTP: TLS Server Hostname Override Is Ignored When Reusing HTTPS Connections
7.5
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 41% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
AI
aiohttp · aio-libs
< 3.14.1 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-54275
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-54275
Third Party Advisory
https://github.com/aio-libs/aiohttp/security/advisories/GHSA-4m7w-qmgq-4wj5
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