curl - improper delegation of client credentials

Richard Silverman discovered that when doing GSSAPI authentication, libcurl
unconditionally performs credential delegation. This hands the server a copy of
the client’s security credentials, allowing the server to impersonate the
client to any other using the same GSSAPI mechanism.
This is obviously a very sensitive operation, which should only be done when
the user explicitly so directs.

For the oldstable distribution (lenny), this problem has been fixed in
version 7.18.2-8lenny5.

For the stable distribution (squeeze), this problem has been fixed in
version 7.21.0-2.

For the testing distribution (wheezy), this problem has been fixed in
version 7.21.6-2.

For the unstable distribution (sid), this problem has been fixed in
version 7.21.6-2.

We recommend that you upgrade your curl packages.