cvssh: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/bin/cvssh - from package: gforge-common

You may install the required package with command apt-get install {package}

Error in other languages:
cvssh: bevel nie gevind nie
cvssh: comandă negăsită
cvssh: comando não encontrado
cvssh: commande introuvable
cvssh: command not found
cvssh: käsku ei ole
cvssh: không tìm thấy lệnh
cvssh: komanda nerasta
cvssh: Kommando nicht gefunden.
cvssh: kommandot finns inte
cvssh: komut yok
cvssh: nie znaleziono polecenia
cvssh: níor aimsíodh an t-ordú
cvssh: no se encontró la orden
cvssh: no s'ha trobat l'ordre
cvssh: opdracht niet gevonden
cvssh: parancs nem található
cvssh: perintah tidak ditemukan
cvssh: príkaz nenájdený
cvssh: příkaz nenalezen
cvssh: команда не найдена
cvssh: командата не е открита
cvssh: 命令找不到
cvssh: コマンドが見つかりません