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OpenSSH 8.0 has an important security fix for a weakness in the scp(1) tool when you use scp for copying files to/from remote systems. Till now when copying files from remote systems to a local directory, SCP was not verifying the filenames of what was being sent from the server to client. This allowed a hostile server to create or clobber unexpected local files with attack-controlled data regardless of what file(s) were actually requested for copying from the remote server. OpenSSH 8.0 adds client-side checking that the filenames sent from the server match the command-line request.
While this client-side checking added to SCP, the OpenSSH developers recommend against using it and instead use sftp, rsync, or other alternatives. “The scp protocol is outdated, inflexible and not readily fixed. We recommend the use of more modern protocols like sftp and rsync for file transfer instead.“, mention OpenSSH developers.
New to OpenSSH 8.0 meanwhile is support for ECDSA keys in PKCS#11 tokens, experimental quantum-computing resistant key exchange method. Also, the default RSA key size from ssh-keygen has been increased to 3072 bits and more SSH utilities supporting a “-v” flag for greater verbosity are added. It also comes with a wide range of fixes throughout including a number of portability fixes.
More details on OpenSSH 8.0 is available on OpenSSH.com.