Improper Certificate Validation in aiohttp - #VU133990
Published: June 9, 2026
Vulnerability identifier: #VU133990
CSH Severity: Medium
CVSS v4.0: 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/U:Green
CVE-ID: N/A
CWE-ID: CWE-295
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: aio-libs
Affected software:
aiohttp
aiohttp
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass TLS hostname verification.
The vulnerability exists due to improper certificate validation in HTTPS connection reuse when reusing an existing connection for later requests with different per-request server_hostname parameters. A remote attacker can cause connection reuse to bypass TLS hostname verification.
Remediation
Install security update from vendor's website.