CVE-2026-86009

Mailu: Domain managers can allow themselves to spoof on other hosted domains they should not control

State: Published
Severity: 8.2 High
Published: Oct 16, 2026
Updated: Oct 21, 2026
Reserved: Sep 4, 2026

Description

Mailu is a mail server distributed as a set of Docker images. Prior to f05aeb8322e2f61096af6b089d61ba6f40587d96, domain managers can enable spoofing for hosted domains they do not control. A potentially malicious domain administrator enables spoofing for another hosted domain and can send emails that are authenticated with DKIM/SPF for domains they should not be able to. This vulnerability is addressed by f05aeb8322e2f61096af6b089d61ba6f40587d96.

Scores

CVSS	Score	Vector	Source
4.0	8.2 High	CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N	GitHub_M

Weaknesses

CWE-285 Improper Authorization
CWE-863 Incorrect Authorization

Affected Products

Product	Versions
MailuMailu	< f05aeb8322e2f61096af6b089d61ba6f40587d96Affected

References

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