It was discovered that pip incorrectly handled unicode separators in git references. A remote attacker could possibly use this issue to install a different revision on a repository.
For Debian 8 jessie, these problems have been fixed in version 1.5.6-5+deb8u2.
We recommend that you upgrade your python-pip packages.
Further information about Extended LTS security advisories can be found at: https://deb.freexian.com/extended-lts/