Threat Intelligence Database

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.

Server-side memory exhaustion in Apache MINA SSHD 1.0.0 to 2.19.0 and 3.0.0-M1 to 3.0.0-M5, component sshd-sftp, in the SFTP v6 check-file-name/check-file-handle extension. Apache MINA SSHD is a Java library for client-side and server-side SSH. Using a very small "block size" (for instance 256, which is the minimum) on a huge file generates many (file size / block size) hashes. The resulting SFTP reply message was accumulated fully in memory server-side, which could, with a suitably large (possibly sparse) file exhaust the server-side memory, taking down the server. Users are recommended to upgrade to version 2.20.0 or 3.0.0-M6, which fix this issue by imposing a maximum limit on the size of the reply. Many SFTP implementations have a general limit on the size of SFTP messages anyway; typically 256kB as in OpenSSH or also in Apache MINA SSHD.