Debian: DSA-3440-1 Urgent Security Issue: Sudo Access Control Flaw

When sudo is configured to allow a user to edit files under a directory
that they can already write to without using sudo, they can actually
edit (read and write) arbitrary files. Daniel Svartman reported that a
configuration like this might be introduced unintentionally if the
editable files are specified using wildcards, for example:

operator ALL=(root) sudoedit /home/*/*/test.txt

The default behaviour of sudo has been changed so that it does not allow
editing of a file in a directory that the user can write to, or that is
reached by following a symlink in a directory that the user can write
to. These restrictions can be disabled, but this is strongly
discouraged.

For the oldstable distribution (wheezy), this problem has been fixed
in version 1.8.5p2-1+nmu3+deb7u1.

For the stable distribution (jessie), this problem has been fixed in
version 1.8.10p3-1+deb8u3.

For the testing distribution (stretch), this problem has been fixed
in version 1.8.15-1.1.

For the unstable distribution (sid), this pro...