Software Update: PuTTY 0.73

A new release of PuTTY has become available. PuTTY is one of the most popular telnet and ssh clients, which makes it possible to remotely manage a computer over a secure connection. Originally, the program was only available for Windows, but today there are also clients for the various Unix platforms. The changelog for since version 0.71 can be found below.

These features are new in 0.73:

  • Security fix: on Windows, other applications were able to bind to the same TCP port as a PuTTY local port forwarding.
  • Security fix: in bracketed paste mode, the terminal escape sequences that should delimit the pasted data were appearing together on one side of it, making it possible to misidentify pasted data as manual keyboard input.
  • Bug fix (possibly security-related): an SSH-1 server sending a disconnection message could cause an access to freed memory.
  • Bug fix: Windows Plink would crash on startup if it was acting as a connection-sharing downstream.
  • Bug fix: Windows PuTTY now updates its terminal window size correctly if the screen resolution changes while it’s maximized.
  • Bug fix: tweaked terminal handling to prevent lost characters at the ends of lines in gcc’s colored error messages.
  • Bug fix: removed a bad interaction between the ‘clear scrollback’ operation and mouse selection that could give rise to the dreaded “line==NULL” assertion box.

These features were new in 0.72:

  • Security fixes found by the EU-funded bug bounty:
    • two separate vulnerabilities affecting the obsolete SSH-1 protocol, both available before host key checking
    • a vulnerability in all the SSH client tools (PuTTY, Plink, PSFTP and PSCP) if a malicious program can impersonate Pageant
  • Bug fix: crash in GSSAPI / Kerberos key exchange affecting third-party GSSAPI providers on Windows (such as MIT Kerberos for Windows)
  • Bug fix: crash in GSSAPI / Kerberos key exchange triggered if the server provided an ordinary SSH host key as part of the exchange
  • Bug fix: trust sigils were never turned off in SSH-1 or Rlogin
  • Bug fix: trust sigils were never turned back on if you used Restart Session
  • Bug fix: PSCP in SCP download mode could create files with a spurious newline at the end of their names
  • Bug fix: PSCP in SCP download mode with the -p option would generate spurious complaints about illegal file renaming
  • Bug fix: the initial instruction message was never printed during SSH keyboard-interactive authentication
  • Bug fix: pasting very long lines through connection sharing could crash the downstream PuTTY window
  • Bug fix: in keyboard layouts with a ‘,’ key on the numeric keypad (eg German), Windows PuTTY would generate ‘.’ instead for that key
  • Bug fix: PuTTYgen could generate RSA keys with a modulus one bit shorter than requested

Version number 0.73
Release status Final
Operating systems Windows 7, Linux, BSD, Windows Vista, Windows Server 2008, Windows Server 2012, Windows 8, Windows 10, Windows Server 2016
Website putty
File size


License type GPL