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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v4.0
Weakness Type (CWE)
References 4
https://github.com/agronholm/anyio/commit/68f58915f82d9be8109ebbbd8f5d70577d43f…
security-advisories@github.com
https://github.com/agronholm/anyio/pull/1208
security-advisories@github.com
https://github.com/agronholm/anyio/releases/tag/4.14.2
security-advisories@github.com
https://github.com/agronholm/anyio/security/advisories/GHSA-82r6-8w77-94w6
security-advisories@github.com