CVE-2026-101278 describes a weakness in the Trusted Domain Project OpenDMARC software up to version 1.4.2. The vulnerability exists in the opendmarc_get_tld function within libopendmarc/opendmarc_tld.c, specifically in the PSL Wildcard Handler component. This flaw allows an attacker to manipulate inputs to cause an origin validation error remotely. The exploit code has been publicly released, but there is no indication of active exploitation in the wild. The vendor was notified early but did not provide any response or remediation guidance.

The vulnerability can be exploited remotely to cause origin validation errors, which may affect the integrity of domain validation processes in OpenDMARC. This could potentially lead to incorrect handling of domain-based message authentication, but the exact impact beyond origin validation error is not detailed. The CVSS score of 5.3 indicates a medium severity level.

No official fix or patch is currently available, and the vendor has not responded to the disclosure. Users should monitor vendor channels for any future updates or advisories. Until a patch is released, consider additional validation controls or compensating measures in the email authentication infrastructure to mitigate risks associated with origin validation errors.