It was discovered that php-horde-core, a set of classes providing the
core functionality of the Horde Application Framework, is prone to a
cross-site scripting vulnerability.
For the stable distribution (jessie), this problem has been fixed in
version 2.15.0+debian0-1+deb8u1.
For the testing distribution (stretch), this problem has been fixed
in version 2.22.4+debian0-1.
For the unstable distribution (sid), this problem has been fixed in
version 2.22.4+debian0-1.
We recommend that you upgrade your php-horde-core packages.