OpenSSH 2.5.1 compatibility problem

[Neal Barney]

SSH server specs:
-----------------------
Redhat Linux 6.2
Custom built 2.2.17 kernel
OpenSSL 0.9.5a (update from RedHat).
OpenSSH 2.5.1p1

         I am using my Linux box as an Internet gateway.  I wanted to keep 
the box as secure as possible while still having the functionality I 
needed.  The only way to connect to my server is through SSH.  A fair 
majority of the time I am attempting to connect to the server from a 
Windows box (whether at work, home, or on the road...).  The software that 
I have used extensively in the past is a great little program called PuTTY 
(http://www.chiark.greenend.org.uk/~sgtatham/putty/).  It supports SSH1 and 
SSH2 protocols.  I have never had any problems in the past using these two 
pieces of software together.  PuTTY has worked flawlessly with OpenSSH 
2.2.0p1 and 2.3.0p1.
         However, using OpenSSH 2.5.1p1 PuTTY will no longer work.  PuTTY 
will briefly flash a window and exit.  No error messages are given from 
PuTTY.  However, the sshd daemon outputs the following line to the Linux 
log file:

Feb 21 10:13:04 rugen sshd[21915]: fatal: xfree: NULL pointer given as argument

Everything works fine if I downgrade to OpenSSH 2.3.0p1.

For completeness sake, I'll include some info about the client machine:

PuTTY version:          0.51 (also downloaded snapshot on Feb 21st, 2001).
OS:                             Windows 98
Connection mode:                SSH

Options selected:
--------------------------
         Connection
Terminal type string            xterm
Auto-login username             (blank) (also tried using local login name)

         SSH
Remote command          (blank)
Attempt TIS or Cryptocard...    (not checked)
Allows agent forwarding (not checked)
Don't allocate a pseudo-term.   (not checked)
Preferred Protocol vers.        SSH2
Preferred Encryption algo.      3DES
Imitate MAC bug in com...       (not checked)

The author of putty (putty at projects.tartarus.org) has already been 
contacted about this problem.  I hope that enough information was given and 
is helpful in locating the problem.