fontconfig - security update

Tobias Stoeckmann discovered that cache files are insufficiently
validated in fontconfig, a generic font configuration library. An
attacker can trigger arbitrary free() calls, which in turn allows double
free attacks and therefore arbitrary code execution. In combination with
setuid binaries using crafted cache files, this could allow privilege
escalation.

For the stable distribution (jessie), this problem has been fixed in
version 2.11.0-6.3+deb8u1.

For the unstable distribution (sid), this problem has been fixed in
version 2.11.0-6.5.

We recommend that you upgrade your fontconfig packages.