PuTTY

<ul>
            <li>Security fix for CVE-2024-31497: NIST P521 / ecdsa-sha2-nistp521 signatures are no longer generated with biased values of k. The previous bias compromises private keys.</li>
          </ul>
        

<ul>
            <li>Security fix: support for OpenSSH's new kex-strict protocol modification, addressing a vulnerability in some @openssh.com cipher and MAC modes, in particular ChaCha20+Poly1305.</li>
            <li>Bug fix: the MSI-installed version of putty.exe can now find its help file again.</li>
            <li>Bug fix: a server sending non-displaying terminal escape sequences such as ESC[0m now no longer resets the scrollback to the bottom of the window.</li>
          </ul>
        

<ul>
            <li>Windows installer scope is back to the normal 'per machine' setting, reverting 0.78's security workaround. Note: this means that installing the 0.79 or later Windows installer will not automatically uninstall 0.78, if 0.78 was installed using its default 'per user' scope. In that situation we recommend uninstalling 0.78 first, if possible. If both end up installed, uninstalling both and then re-installing the new version will fix things up.</li>
            <li>Terminal mouse tracking: support for mouse movements which are not drags.</li>
            <li>Terminal mouse tracking: support for horizontal scroll events (e.g. generated by trackpads).</li>
            <li>Backwards compatibility fix: certificate-based user authentication now works with OpenSSH 7.7 and earlier.</li>
            <li>Bug fix: in a session using the 'Raw' protocol, pressing ^D twice in the terminal window could cause an assertion failure.</li>
            <li>Bug fix: terminal output could hang if a resize control sequence was sent by the server (and was not disabled in the Features panel) but PuTTY's window was set to non-resizable in the Window panel.</li>
            <li>Bug fix: GTK PuTTY could fail an assertion if a resize control sequence was sent by the server while the window was docked to one half of the screen in KDE.</li>
            <li>Bug fix: GTK PuTTY could fail an assertion if you tried to change the font size while the window was maximised.</li>
            <li>Bug fix: the 'bell overload' timing settings were misinterpreted by Unix PuTTY and pterm 0.77/0.78; if any settings were saved using these versions, confusion can persist with newer versions.</li>
            <li>Bug fix: SSH authentication banners were not reliably printed if a server sent one immediately before closing the connection (e.g. intended as a user-visible explanation for the connection closure).</li>
            <li>Bug fix: the 'close' command in PSFTP always reported failure, so that ending a psftp -b batch script with it would cause PSFTP as a whole to believe it had failed, even if everything worked fine.</li>
            <li>Bug fix: certificate handling would do the wrong thing, for RSA keys only, if you specified a detached certificate to go with a PPK file that had a different certificate embedded.</li>
            <li>Bug fix: Windows Pageant's option to write out a configuration file fragment for Windows OpenSSH now works even if you have a space in your user name.</li>
            <li>Bug fix: in local-line-editing mode, pressing ^U now just clears the line, instead of clearing it and then inserting a literal ^U.</li>
            <li>Several bug fixes in edge cases of terminal wrapping, involving double-width characters.</li>
          </ul>
        

<ul>
            <li>Support for OpenSSH certificates, for both user authentication keys and host keys.</li>
            <li>New SSH proxy modes, for running a custom shell command or subsystem on the proxy server instead of forwarding a port through it.</li>
            <li>New plugin system to allow a helper program to provide responses in keyboard-interactive authentication, intended to automate one-time password systems.</li>
            <li>Support for NTRU Prime post-quantum key exchange.</li>
            <li>Support for AES-GCM (in the OpenSSH style rather than RFC 5647).</li>
            <li>Support for more forms of Diffie-Hellman key exchange: new larger integer groups (such as group16 and group18), and support for using those and ECDH with GSSAPI.</li>
            <li>Bug fix: the 32-bit Windows build now runs on Windows XP again.</li>
            <li>Bug fix: server-controlled window title setting now works again even if the character set is ISO 8859 (or a few other affected single-byte character sets).</li>
            <li>Bug fix: certain forms of OSC escape sequences (sent by some real servers) could cause PuTTY to crash.</li>
            <li>Bug fix: the -pwfile/-pw options no longer affect local key passphrase prompts, and no longer suppress Plink's anti-spoofing measures.</li>
            <li>Note: installing the 0.78 or later Windows installer will not automatically uninstall 0.77 or earlier, due to a change we've made to work around a bug. We recommend uninstalling the old version first, if possible. If both end up installed, uninstalling both and then re-installing the new version will fix things up.</li>
          </ul>
        

PuTTY

SSH, Telnet and Rlogin client

Changes in version 0.81

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