APT before 1.0.9 does not "invalidate repository data" when moving from an unauthenticated to authenticated state, which allows remote attackers to have unspecified impact via crafted repository data.
Exploitability
AV:NAC:MAu:NImpact
C:PI:PA:P6.8/AV:N/AC:M/Au:N/C:P/I:P/A:P