CVE-2026-114478 Progressive Robot Ltd CVE debrief

Who should care

Defenders responsible for hMailServer configurations, especially those with forwarding enabled, should assess exposure to potential email spoofing attacks and verify configurations to prevent exploitation. This includes reviewing the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.

Why it matters

Defenders should prioritize verifying hMailServer configurations, especially those with forwarding enabled, and assess exposure to potential email spoofing attacks due to insufficient preservation of the original sender in the forwarding of Progressive Robot hMailServer 6.0.0 through 6.3.6.

• Potential email spoofing attacks
• Bypassing of DMARC policy checks
• Delivery of malicious emails to unintended recipients
• Possible exploitation requires verification

Technical summary

The vulnerability allows remote unauthenticated attackers to have mail delivered to other receivers as passing a domain's DMARC policy by insufficient preservation of the original sender in the forwarding of Progressive Robot hMailServer 6.0.0 through 6.3.6. This occurs when the server sends on a copy of mail that came from outside - an account's forward, a mail rule's forward, a Sieve redirect, a list's copy, or an alias or list expanding to an outside address. The server could give the copy an SMTP identity in the organisation of the domain the copy's From names, whatever the message's origin.

Defensive priority

Defenders should prioritize verifying hMailServer configurations, especially those with forwarding enabled, and assess exposure to potential email spoofing attacks.

Recommended defensive actions

• Verify hMailServer configurations, especially those with forwarding enabled
• Assess exposure to potential email spoofing attacks
• Update to version 6.3.7 or later if possible
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, but limited information is available on potential exploitation or affected versions beyond 6.0.0 through 6.3.6. The vulnerability allows remote unauthenticated attackers to have mail delivered to other receivers as passing a domain's DMARC policy by insufficient preservation of the original sender in the forwarding of Progressive Robot hMailServer 6.0.0 through 6.3.6. There is a risk of email spoofing attacks and bypassing of DMARC policy checks. Defenders should

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.