CVE-2026-54275
aiohttp: TLS Server Hostname Override Is Ignored When Reusing HTTPS Connections
Description
### Summary The `server_hostname` TLS SNI check can be bypassed when an existing connection is reused. ### Impact 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. ### Workaround Disable keep_alive if you need to change the `server_hostname` check between requests. ----- Patch: https://github.com/aio-libs/aiohttp/commit/0ca2b6c28a25726527a8b60f25960262a91ed0e0
How to fix CVE-2026-54275
To remediate CVE-2026-54275, upgrade the affected package to a fixed version below.
- —upgrade to 3.14.1 or later
Is CVE-2026-54275 being exploited?
No exploitation signal available. Neither CISA KEV nor a current EPSS score has been published for CVE-2026-54275.
Affected packages (1)
- from 0, < 3.14.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | 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 |