Spoofing Vulnerability in Mailu Mail Server by Mailu
CVE-2026-86009

8.2HIGH

Key Information:

Vendor

Mailu

Status
Mailu
Vendor
CVE Published:
16 October 2026

What is CVE-2026-86009?

Mailu, a mail server implemented as Docker images, has a vulnerability that allows domain managers to enable email spoofing for domains outside of their control. This issue permits a potentially malicious domain administrator to send authenticated emails using DKIM and SPF mechanisms for domains they should not have access to. The vulnerability has been addressed in a specific commit, enhancing the security of Mailu's email handling.

Affected Version(s)

Mailu < f05aeb8322e2f61096af6b089d61ba6f40587d96

References

https://github.com/Mailu/Mailu/security/advisories/GHSA-c...
x_refsource_CONFIRM
https://github.com/Mailu/Mailu/issues/2686
x_refsource_MISC
https://github.com/Mailu/Mailu/pull/4072
x_refsource_MISC

CVSS V4

Score:
8.2
Severity:
HIGH
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.