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CRITICAL

GHSA-82r6-8w77-94w6

AnyIO: TLSStream IDNA 2003 host name encoding enables potential TLS certificate spoofing

Quick fix

GHSA-82r6-8w77-94w6 — anyio: upgrade to the fixed version with the command below.

pip install --upgrade 'anyio>=4.14.2'

Details

### Impact Services using internationalized (non-ASCII) domain names are potentially vulnerable to TLS connections made from AnyIO's `connect_tcp()` or directly via `TLSStream.wrap()` where the connection has (through other means) been hijacked and redirected to a malicious server. The attacker would obtain a legitimate certificate using the IDNA 2003 encoded version of the domain name and offer it to the connecting client, making the certificate validate properly on the client's end.

### Patches The vulnerability will be patched in v4.14.2.

### Workarounds Encode host names via the `idna` package prior to connecting.

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/anyio
Introduced in: 0Fixed in: 4.14.2
Fixpip install --upgrade 'anyio>=4.14.2'

References