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.
Disable keep_alive if you need to change the server_hostname check between requests.
Patch: https://github.com/aio-libs/aiohttp/commit/0ca2b6c28a25726527a8b60f25960262a91ed0e0
{
"nvd_published_at": null,
"github_reviewed_at": "2026-06-15T20:11:13Z",
"github_reviewed": true,
"severity": "LOW",
"cwe_ids": [
"CWE-297"
]
}