CVE-2026-86009

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

8.2 High

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.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: High
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: High
Availability: None

Exploit likelihood

0.38%Up 0.1 points since Oct 17, 2026

What each source reports

CVE List Score used 8.2

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

Record: CVE-2026-86009
CVSS 4.0: 8.2 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N
Weakness: CWE-285, CWE-863
Updated: 2026-11-02

EUVDEUVD-2026-102922 8.2

Record: EUVD-2026-102922
CVSS 4.0: 8.2 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N
Updated: 2026-11-02

NVD 8.2

Record: CVE-2026-86009
CVSS 4.0: 8.2 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness: CWE-285, CWE-863
Updated: 2026-11-02

OSV 8.2

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

Record: CVE-2026-86009
CVSS 4.0: 8.2 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N
Weakness: CWE-285, CWE-863
Updated: 2026-11-02

Affected products

mailu

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-86009 is a high vulnerability (CVSS 8.2) in Mailu, published October 16, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.38%, the 31st percentile. No source names a fixed version.