CVE-2026-55973

A flaw was found in Unbound. When the 'dns-error-reporting: yes' option is enabled, a remote attacker can send a specially crafted DNS response containing a malformed EDNS Report-Channel option from a delegated zone they control. This can lead to a stack variable overwrite, causing the Unbound daemon to terminate. This vulnerability results in a denial of service.

This Important denial of service flaw in Unbound occurs when the dns-error-reporting option is explicitly enabled, allowing a remote attacker to terminate the daemon with a crafted DNS response. While several Red Hat products are affected, many Red Hat Enterprise Linux and OpenShift Container Platform versions are not vulnerable as the affected code is not present.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.