What’s Vulnerable › Vulnerabilities
CVE-2026-54275: AIOHTTP: TLS Server Hostname Override Is Ignored When Reusing HTTPS Connections
- Severity: high (CVSS 7.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.5% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-06-22 · updated 2026-10-25
- Weakness: CWE-297
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 products
- aio-libs aiohttp: before 3.14.1 — fixed in 3.14.1
- Pypi Aiohttp: before 3.14.1; 0.1, 0.10.0, 0.10.1, 0.10.2, 0.11.0, 0.12.0 (+301) — fixed in 3.14.1
How to fix
Upgrade to a fixed version: aio-libs aiohttp 3.14.1; Pypi Aiohttp 3.14.1. Check the vendor advisory for mitigations.
References
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