Daniel Danner discovered that tmux, a terminal multiplexer, is not
properly dropping group privileges. Due to a patch introduced by
Debian, when invoked with the -S option, tmux is not dropping
permissions obtained through its setgid installation (CVE-2011-1496).

For the lenny-backports distribution this problem has been fixed in
version 1.3-2+squeeze1~bpo50+1.

For the squeeze-backports distribution this problem has been fixed in
version 1.4-6~bpo60+1.

For the stable distribution (squeeze), this problem has been fixed
in version 1.3-2+squeeze1.

For the testing distribution (wheezy), this problem has been fixed
in version 1.4-6.

For the unstable distribution (sid), this problem has been fixed in
version 1.4-6.

Upgrade instructions
--------------------

If you don't use pinning (see [1]) you have to update the package
manually via "apt-get -t lenny-backports install <packagelist>" with
the packagelist of your installed packages affected by this update.
[1] <https://backports.debian.org/Instructions>

We recommend to pin (in /etc/apt/preferences) the backports repository
to 200 so that new versions of installed  backports will be installed
automatically.

  Package: *
  Pin: release a=lenny-backports
  Pin-Priority: 200