(RHSA-2024:2587) Important: unbound security update

The unbound packages provide a validating, recursive, and caching DNS or
DNSSEC resolver.

Security Fix(es):

• bind9: KeyTrap - Extreme CPU consumption in DNSSEC validator
  (CVE-2023-50387)

• bind9: Preparing an NSEC3 closest encloser proof can exhaust CPU
  resources (CVE-2023-50868)

• A vulnerability was found in Unbound due to incorrect default
  permissions, allowing any process outside the unbound group to modify the unbound runtime configuration. The default combination of the “control-use-cert: no” option with either explicit or implicit use of an IP address in the “control-interface” option could allow improper access. If a process can connect over localhost to port 8953, it can alter the configuration of unbound.service. This flaw allows an unprivileged local process to manipulate a running instance, potentially altering forwarders, allowing them to track all queries forwarded by the local resolver, and, in some cases, disrupting resolving altogether.

To mitigate the vulnerability, a new file “/etc/unbound/conf.d/remote-control.conf” has been added and included in the main unbound configuration file, “unbound.conf”. The file contains two directives that should limit access to unbound.conf:

control-interface: "/run/unbound/control"
control-use-cert: "yes"

For details about these directives, run “man unbound.conf”.

Updating to the version of unbound provided by this advisory should, in
most cases, address the vulnerability. To verify that your configuration is not vulnerable, use the “unbound-control status | grep control” command. If the output contains “control(ssl)” or “control(namedpipe)”, your configuration is not vulnerable. If the command output returns only “control”, the configuration is vulnerable because it does not enforce access only to the unbound group members. To fix your configuration, add the line “include: /etc/unbound/conf.d/remote-control.conf” to the end of the file “/etc/unbound/unbound.conf”. If you use a custom “/etc/unbound/conf.d/remote-control.conf” file, add the new directives to
this file. (CVE-2024-1488)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.