CVE-2026-107584
Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-107584 is a high-severity Failing Open (CWE-636) vulnerability. Its CVSS base score is 7.4 (High).
Operationally, ranked at the 4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-94867
Vulnerability Data
Progressive Robot hMailServer 6.0.0 through 6.3.5 fails open when applying DANE (RFC 7672) to outbound SMTP delivery. The server's validating DNSSEC resolver treated a TLSA or MX lookup that did not complete (no answer, SERVFAIL, a malformed reply), an answer…
more
without the requested records and without an NSEC/NSEC3 proof of their absence, and an answer whose records carried no applicable RRSIG as if the recipient domain were unsigned, and from 6.2.19 it also delivered to mail exchangers taken from an unvalidated MX lookup that the DNSSEC-validated MX record set did not name. An attacker who can drop, forge or strip DNS answers on the path to the server's resolver, at the resolver, or between the resolver and the recipient domain's name servers, and who holds an active position on the SMTP path, can thereby disable DANE for a DNSSEC-signed recipient domain and cause messages to be delivered in cleartext or to a host of the attacker's choosing with an arbitrary certificate, where they can be read and modified.
- CWE(s)
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Ensures audit logging continues on primary failure instead of failing open with no logging capability.
Supports failing securely by requiring alerts and configurable actions (e.g., shutdown) when the audit mechanism fails instead of continuing without it.
Entering safe mode when conditions are detected prevents failing open and continuing normal operation in a potentially exploitable state.
Ensures security functions remain enforced via alternatives instead of defaulting to an insecure state when the primary means fails.
Fail-safe-defaults principle prevents systems from failing open.
Directly requires transition to a known (secure) state on failure, preventing fail-open behavior.
Standby components and explicit exchange criteria enforce a controlled, secure failover instead of failing open.
Directly implements fail-safe (fail-closed/secure) behavior on indicated failures, preventing the system from defaulting to an insecure open state.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.
- No fine-grained STIG row for CWE-636, a class-level weakness, and none of its children carries one either.