It is adviced to update the ca_root_certifcates package.
To do this use this command in the Terminal or update the system via SoftwareUpdater:
pkgman update ca_root_certificates
Intermediate certs were compromised, that means actors who have this key can fake the identity of https servers (or other TLS servers) towards the Operating System
More info:
Do a reboot needed ? Or only restarting apps ? Or it apply fully live as soon as the ca_root_certificates package was updated, without restarting anything?
If you use the pkgman command then it is sufficient to restart only WebPositive if it was running and maybe re-start the mail daemon (quit it with taskmonitor). For ported applications this probably also applies (but depends on how they deal with connections)
If you install an update that also updates haiku.hpkg, such as on an older beta or nightly the updated package won’t apply right away, so in that case you’d need to reboot
So, to be sure, I strongly suggest to reboot after update. It’s perfect time to benefit from fast shutdown fast boot time of Haiku 
As a small update to this, the issue is not only that private keys of these intermediate CAs have been compromised, but also that they used such weak keys that they can be gotten easily. One apparently had the number “4” as private key… so a motivated attacker can easily use this when an old cert store is in use
How in the world…