CVE-2026-63374 (GCVE-0-2026-63374)
Vulnerability from cvelistv5
Published
2026-09-22 15:23
Modified
2026-09-28 16:32
Severity ?
9.3 (Critical) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CWE
  • CWE-295 - Improper Certificate Validation
  • CWE-297 - Improper Validation of Certificate with Host Mismatch
Summary
AnyIO is a high level asynchronous concurrency and networking framework that works on top of either Trio or asyncio. Prior to 4.14.2, connect_tcp() and TLSStream.wrap() can validate internationalized host names after the standard library converts them with IDNA 2003 instead of IDNA 2008. When a connection to a non-ASCII domain is hijacked or redirected, an attacker can obtain a legitimate certificate for the different ASCII hostname produced by IDNA 2003 and present it to the client, causing the malicious endpoint's certificate to validate. This issue is fixed in version 4.14.2.
References
Impacted products
Vendor Product Version
agronholm anyio Version: < 4.14.2
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