| Title | The Trusted Domain Project OpenDMARC 1.4.2 Improper Authentication |
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| Description | OpenDMARC incorrectly stops DMARC policy discovery when a subdomain publishes a record with an unsupported or malformed version value. Instead of discarding the unusable record and continuing the organizational-domain lookup, OpenDMARC returns `dmarc=permerror` and does not apply the parent domain’s `sp=` policy.
As a result, a subdomain that should be protected by a parent-level `sp=reject` or `sp=quarantine` policy may be treated as having no enforceable DMARC policy. A remote unauthenticated attacker can exploit the condition by sending forged messages from an affected subdomain.
The issue requires an unusable DMARC record, such as one containing `v=DMARC2` or `v=DMARC1.0`, to exist at the subdomain. If no record is present, OpenDMARC correctly continues to the parent domain. |
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| Source | ⚠️ https://xuyongzhe-vt.github.io/share/opendmarc-subdomain-walk-abort.html |
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| User | yongzhe_xu (UID 100420) |
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| Submission | 08/07/2026 04:38 (2 months ago) |
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| Moderation | 09/27/2026 13:33 (2 months later) |
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| Status | Accepted |
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| VulDB entry | 410887 [Trusted Domain Project OpenDMARC up to 1.4.2 opendmarc_policy.c strcasecmp exceptional condition] |
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| Points | 20 |
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