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Gentoo Linux Advisory: PuTTY

Oct 28, 2004, 17:58 (1 Talkback[s])

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Gentoo Linux Security Advisory GLSA 200410-29

Severity: Normal
Title: PuTTY: Pre-authentication buffer overflow
Date: October 27, 2004
Bugs: #69123
ID: 200410-29


PuTTY contains a vulnerability allowing an SSH server to execute arbitrary code on the connecting client.


PuTTY is a free implementation of Telnet and SSH for Win32 and Unix platforms, along with an xterm terminal emulator.

Affected packages

Package Vulnerable Unaffected
1 net-misc/putty <= 0.55 >= 0.56


PuTTY fails to do proper bounds checking on SSH2_MSG_DEBUG packets. The "stringlen" parameter value is incorrectly checked due to signedness issues. Note that this vulnerability is similar to the one described in GLSA 200408-04 but not the same.


When PuTTY connects to a server using the SSH2 protocol, an attacker may be able to send specially crafted packets to the client, resulting in the execution of arbitrary code with the permissions of the user running PuTTY. Note that this is possible during the authentication process but before host key verification.


There is no known workaround at this time.


All PuTTY users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=net-misc/putty-0.56"


[ 1 ] iDEFENSE Security Advisory 10.27.04

[ 2 ] PuTTY ChangeLog


This GLSA and any updates to it are available for viewing at the Gentoo Security Website:


Security is a primary focus of Gentoo Linux and ensuring the confidentiality and security of our users machines is of utmost importance to us. Any security concerns should be addressed to or alternatively, you may file a bug at


Copyright 2004 Gentoo Foundation, Inc; referenced text belongs to its owner(s).

The contents of this document are licensed under the Creative Commons - Attribution / Share Alike license.