Possible memory exhaustion in SFTP clients (DefaultSftpClient) in component sshd-sftp in Apache MINA SSHD versions 0.9.0 to 2.19.0 and 3.0.0-M1 to 3.0.0-M5. Apache MINA SSHD is a Java library for client-side and server-side SSH. The sshd-sftp component provides support for SFTP. The SFTP client implementation, when receiving a reply, did not check that this reply corresponded to a request sent earlier. Unsolicited replies would be stored but never consumed. A malicious server could keep sending unsolicited replies until available memory in the client was exhausted. Users are recommended to upgrade to version 2.20.0 or 3.0.0-M6, which fix this issue.