Vulnerability · Published Oct 16, 2026 · Assigned by GitHub_M

CVE-2026-86009Mailu: Domain managers can allow themselves to spoof on other hosted domains they should not control

High 8.2

In plain English

A high-severity incorrect authorization in Mailu from Mailu. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities).

Severity (CVSS 4.0)8.2High

Exploit odds (30 days)0.4%top 68.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
Mailu	Mailu	< f05aeb8322e2f61096af6b089d61ba6f40587d96

Weakness: CWE-285, CWE-863 · Vector: 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

References

https://github.com/Mailu/Mailu/security/advisories/GHSA-crww-m82r-2wfm x_refsource_CONFIRM
https://github.com/Mailu/Mailu/issues/2686 x_refsource_MISC
https://github.com/Mailu/Mailu/pull/4072 x_refsource_MISC
https://github.com/Mailu/Mailu/commit/f05aeb8322e2f61096af6b089d61ba6f40587d96 x_refsource_MISC