Debian 8 Jessie: DLA-1637-1 Moderate: APT Man-In-The-Middle Threat

apt -o Acquire::http::AllowRedirect=false update
apt -o Acquire::http::AllowRedirect=false upgrade

This is known to break some proxies when used against security.debian.org. If
that happens, people can switch their security APT source to use:

deb stable/updates main

For Debian 8 "Jessie", this problem has been fixed in version
1.0.9.8.5.

We recommend that you upgrade your apt packages.

Specific upgrade instructions:

If upgrading using APT without redirect is not possible in your situation, you
can manually download the files (using wget/curl) for your architecture using
the URL provided below, verifying that the hashes match. Then you can install
them using dpkg -i.

Architecture independent files:

Size/SHA256 checksum: 301106 47df9567e45fadcd2a56c0fd3d514d8136f2f206aa7baa47405c6fcb94824ab6
Size/SHA256 checksum: 750506 ce79b2ef272716b8da11f3fd0497ce0b7ee69c9c66d01669e8abbbfdde5e6256

amd64 architecture: