CVE-2020-26278

Weave Net is open source software which creates a virtual network that connects
Docker containers across multiple hosts and enables their automatic discovery. 
Weave Net before version 2.8.0 has a vulnerability in which can allow an
attacker to take over any host in the cluster.

Weave Net is supplied with a manifest that runs pods on every node in a
Kubernetes cluster, which are responsible for managing network connections for
all other pods in the cluster. This requires a lot of power over the host, and
the manifest sets `privileged: true`, which gives it that power.
It also set `hostPID: true`, which gave it the ability to access all other
processes on the host, and write anywhere in the root filesystem of the host.
This setting was not necessary, and is being removed.

You are only vulnerable if you have an additional vulnerability (e.g. a bug in
Kubernetes) or misconfiguration that allows an attacker to run code inside the
Weave Net pod,
No such bug is known at the time of release, and there are no known instances of
this being exploited.

Weave Net 2.8.0 removes the hostPID setting and moves CNI plugin install to an
init container.

Users who do not update to 2.8.0 can edit the hostPID line in their existing
DaemonSet manifest to say false instead of true,
arrange some other way to install CNI plugins (e.g. Ansible) and remove those
mounts from the DaemonSet manifest.

References:
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2020-26278
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26278
https://github.com/weaveworks/weave/blob/master/CHANGELOG.md#release-280
https://github.com/weaveworks/weave/commit/a0ac81b3b4cae6d0dcaf3732fd91cedefc89f720
https://github.com/weaveworks/weave/pull/3876
https://github.com/weaveworks/weave/security/advisories/GHSA-pg3p-v8c6-c6h3