eParakstītājs 3.0 for Windows – remote code execution via unauthenticated auto-update

eParakstītājs 3.0 for Windows before version
1.10.0 retrieves and executes its automatic updates over a channel that is not
authenticated or integrity-protected. On each launch the application fetches an
update descriptor (XML) over TLS but accepts any TLS certificate (a permissive
TrustManager and a HostnameVerifier that always returns true), does not verify
any digital signature on the update descriptor, and does not verify the
Authenticode signature or a checksum of the downloaded installer before running
it. A man-in-the-middle attacker able to redirect www.eparaksts.lv can serve a
crafted update descriptor pointing to an attacker-controlled executable, which
the client downloads and executes, resulting in arbitrary code execution on the
victim host.