{"id":"CVE-2026-54275","aliases":["GHSA-4m7w-qmgq-4wj5","PYSEC-2026-237"],"url":"https://o3.security/vulnerability/CVE-2026-54275","summary":"AIOHTTP: TLS Server Hostname Override Is Ignored When Reusing HTTPS Connections","details":"### Summary\n\nThe `server_hostname` TLS SNI check can be bypassed when an existing connection is reused.\n\n### Impact\n\nIf 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.\n\n### Workaround\n\nDisable keep_alive if you need to change the `server_hostname` check between requests.\n\n-----\n\nPatch: https://github.com/aio-libs/aiohttp/commit/0ca2b6c28a25726527a8b60f25960262a91ed0e0","published":"2026-06-22T16:34:56.184Z","modified":"2026-10-21T02:58:32.555818273Z","cvss":null,"epss":{"score":0.00266,"percentile":0.18626,"asOf":"2026-09-16"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"aiohttp","fixedVersion":"3.14.1"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54275.json"},{"type":"ADVISORY","url":"https://github.com/aio-libs/aiohttp/security/advisories/GHSA-4m7w-qmgq-4wj5"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54275"},{"type":"PACKAGE","url":"https://github.com/aio-libs/aiohttp"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:58:32.555818273Z"}}