CVE-2026-114478 Unintended Proxy or Intermediary ('Confused Deputy') in hMailServer
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-114478?
CVE-2026-114478 is a medium-severity vulnerability in Progressive Robot Ltd hMailServer, published on 21 Oct 2026.
Official description
Insufficient preservation of the original sender in the forwarding of Progressive Robot hMailServer 6.0.0 through 6.3.6 allows a remote unauthenticated attacker to have mail they write, naming in its From an address at a domain the server hosts, delivered to other receivers as passing that domain's DMARC policy. When the server sent 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 - it could give the copy an SMTP identity in the organisation of the domain the copy's From names, whatever the message's origin: with the Sender Rewriting Scheme or the rewrite of the envelope sender on forwarding enabled (both off by default), an address at the forwarding domain; for a list, its bounce address; for a message with an empty envelope sender, none, under the server's own host name; and an envelope sender the message came with at a subdomain of a hosted domain was kept. Where that identity's SPF record authorises the server, other receivers' SPF check of the copy passed for a domain aligned with the From, and DMARC passed with it, although the message had not passed DMARC when the server received it. Exploitation needs a forward, redirect, alias or list that carries the hosted domain's mail to an outside address, and one of: SRS or the envelope rewrite enabled; a list whose bounce address is in the domain's organisation; an envelope sender at a subdomain whose SPF record authorises the server; or, for an empty envelope sender, an SPF record that authorises the server under its host name. The DKIM route to the same result is CVE-2026-107567.
Weakness: CWE-441
Which versions are affected by CVE-2026-114478?
How do I fix CVE-2026-114478?
No fix has been published for CVE-2026-114478 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-114478 being exploited?
There is no known exploitation of CVE-2026-114478 in the wild and no public exploit code.
Sources
Also known as GHSA-w852-m7j4-xm48.