CVE-2026-114474 Use of Less Trusted Source in hMailServer
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-114474?
CVE-2026-114474 is a medium-severity vulnerability in Progressive Robot Ltd hMailServer, published on 21 Oct 2026.
Official description
Use of a less trusted source for the envelope sender in the external-account download of Progressive Robot hMailServer 6.0.0 through 6.3.6 allows a remote unauthenticated attacker to have mail they write in the name of a domain the server hosts sent on by the server with an envelope sender at that domain, so that it passes the domain's SPF and DMARC at other receivers. A message the server downloads from an external POP3 or IMAP account has no SMTP envelope of its own, and the server took the address in its From header as its envelope sender, whatever that address was. A forward or redirect of the downloaded message to an outside address then left with that address as its envelope sender, which the Sender Rewriting Scheme leaves alone for a hosted domain, so that the receiver's SPF check passed for the forged domain, aligned even under strict alignment, with no non-default setting, host name record or DMARC policy needed. An attacker needs to know a mailbox elsewhere that an account here collects and forwards to an outside address; an account holder who adds an external account of their own can collect from a server of their own, which matters where SmtpAuthenticatedSenderCheck holds signed-in senders to their own addresses.
Weakness: CWE-348
Which versions are affected by CVE-2026-114474?
How do I fix CVE-2026-114474?
No fix has been published for CVE-2026-114474 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-114474 being exploited?
There is no known exploitation of CVE-2026-114474 in the wild and no public exploit code.
Sources
Also known as GHSA-q9cg-xjph-9q7j.