Felix Wilhelm of Google Project Zero discovered a flaw in git, a fast, scalable, distributed revision control system. With a crafted URL that contains a newline, the credential helper machinery can be fooled to return credential information for a wrong host.
For Debian 7 Wheezy, these problems have been fixed in version 1:18.104.22.168-1+wheezy9.
We recommend that you upgrade your git packages.
Further information about Extended LTS security advisories can be found at: https://deb.freexian.com/extended-lts/