@hinketu_n https://www.openwall.com/lists/oss-security/2024/03/29/4 をざっくり読んだ限り、sshdが公開鍵認証をする過程で何かのコードを実行しているみたいだ、とのことです。
> Since this is running in a pre-authentication context, it seems likely to allow some form of access or other form of remote code execution.