Debian 8: DLA-1932-1 Urgent: OpenSSL Security Fix to Mitigate Attacks

Normally in OpenSSL EC groups always have a co-factor present and
this is used in side channel resistant code paths. However, in some
cases, it is possible to construct a group using explicit parameters (instead of using a named curve). In those cases it is possible that
such a group does not have the cofactor present. This can occur even
where all the parameters match a known named curve. If such a curve
is used then OpenSSL falls back to non-side channel resistant code
paths which may result in full key recovery during an ECDSA
signature operation. In order to be vulnerable an attacker
would have to have the ability to time the creation of a large
number of signatures where explicit parameters with no co-factor
present are in use by an application using libcrypto. For the
avoidance of doubt libssl is not vulnerable because explicit
parameters are never used.

CVE-2019-1563

In situations where an attacker receives automated notification of