CVE-2026-100891
Description
A flaw was found in OpenDMARC. An encoding error in the Internationalized Domain Name (IDN) handler within the opendmarc_policy_query_dmarc function can cause domain name queries to fail or process incorrectly. A remote attacker could exploit this vulnerability by submitting specially crafted domain names, leading to improper email authentication policy evaluation or service disruption.
Statement
This vulnerability is rated as Important severity because unauthenticated remote senders can transmit messages containing malformed internationalized domain names to trigger parsing failures during policy checks, which can circumvent validation safeguards or interrupt message processing. OpenDMARC is not packaged in supported Red Hat Enterprise Linux repositories and is distributed through the EPEL repository. Systems running an MTA configured with this milter are susceptible if processing inbound email directly from external, untrusted sources.
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