Debian LTS: Security Advisory for avahi (DLA-3047-1)

The remote host is missing an update for the 'avahi' package(s) announced via the DLA-3047-1 advisory.

It was discovered that the Debian package of Avahi, a framework for Multicast DNS Service Discovery, executed the script avahi-daemon-check-dns.sh with root privileges which would allow a local attacker to cause a denial of service or create arbitrary empty files via a symlink attack on files under /var/run/avahi-daemon. This script is now executed with the privileges of user and group avahi and requires sudo in order to achieve that. The aforementioned script has been removed from Debian 10 'Buster' onwards. The workaround could not be implemented for Debian 9 'Stretch' because libnss-mdns 0.10 does not provide the required functionality to replace it. Furthermore it was found (CVE-2021-3468) that the event used to signal the termination of the client connection on the avahi Unix socket is not correctly handled in the client_work function, allowing a local attacker to trigger an infinite loop.

'avahi' package(s) on Debian Linux.

Checks if a vulnerable package version is present on the target host.

For Debian 9 stretch, these problems have been fixed in version 0.6.32-2+deb9u1. We recommend that you upgrade your avahi packages.