[linux-security] xemacs vulnerability

[Martin Siegert <siegert@sfu.ca>]

Topic
=====
buffer overflow in gnuserv compromises security when running xemacs.

Problem Description
===================
Gnuserv is a remote control facility for Emacsen
which is available as standalone program as well as included in
XEmacs21.  Gnuserv has a buffer for which insufficient boundary checks
were made.  Unfortunately this buffer affected access control to
gnuserv which is using a MIT-MAGIC-COOCKIE based system.  It is
possible to overflow the buffer containing the cookie and disable the
cookie comparison. This could lead into a remote user issue commands under
the UID of the person running gnuserv.

Affected Systems
================
xemacs versions prior to 21.1.14

Workaround
==========
Use emacs.

Solution
========
upgrade to version 21.1.14

Debian 2.2 (potato)
-------------------
upgrade the following packages:
gnuserv_2.1alpha-5.1_i386.deb, xemacs21-bin_21.1.10-5_i386.deb,
emacs21-mule-canna-wnn_21.1.10-5_i386.deb, xemacs21-mule_21.1.10-5_i386.deb,
xemacs21-nomule_21.1.10-5_i386.deb

RedHat 6.x
----------
RedHat 6.x does not have xemacs included, it is available as part of the
powertools packages. If you installed it:
rpm -Fvh xemacs-21.1.14-2.62.i386.rpm xemacs-el-21.1.14-2.62.i386.rpm \
         xemacs-info-21.1.14-2.62.i386.rpm

RedHat 7.0
----------
rpm -Fvh xemacs-21.1.14-2.7.i386.rpm xemacs-el-21.1.14-2.7.i386.rpm \
         xemacs-info-21.1.14-2.7.i386.rpm 

Remark with respect to RedHat 6.x, 7.0:
the new packages obsolete xemacs-mule (this is now compiled into the
main binary), xemacs-static, xemacs-extras and xemacs-noX.