Debian Stretch DLA-2527-1 Critical: Snapd Encryption Issue CVE-2019-11840

CVE-2019-11840

An issue was discovered in supplementary Go cryptography libraries, aka
golang-googlecode-go-crypto. If more than 256 GiB of keystream is
generated, or if the counter otherwise grows greater than 32 bits, the amd64
implementation will first generate incorrect output, and then cycle back to
previously generated keystream. Repeated keystream bytes can lead to loss of
confidentiality in encryption applications, or to predictability in CSPRNG
applications.

For Debian 9 stretch, this problem has been fixed in version
2.21-2+deb9u1.

We recommend that you upgrade your snapd packages.

For the detailed security status of snapd please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/source-package/snapd

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS