CVE-2026-86009: high-severity vulnerability in Mailu
Mailu: Domain managers can allow themselves to spoof on other hosted domains they should not control
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.2epss 0.4%
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.
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
Affected products
Mailu · MailuRelated CVEs — Mailu
In the same product, most dangerous first.
CVE-2020-5239HIGHUnspecified vulnerability in the fetchmail script in MailuEPSS 0.9%CVE-2026-85751CRITICALMailu: Authentication bypass in header-based proxy authentication via spoofable `X-Forwarded-By` trustEPSS 0.6%CVE-2026-49217HIGHMailu missing authentication on PATCH /api/v1/token/<id>, which allows unauthenticated removal of IP restrictionsEPSS 0.4%CVE-2026-86008HIGHMailu domain managers can take over higher-privileged accountsEPSS 0.3%