Email Spoofing Vulnerability in OVH Mail Servers
CVE-2026-33586

6.3MEDIUM

Key Information:

Vendor

OvHCL Softwareoud

Status
OvHCL Softwareoud
Vendor
CVE Published:
7 October 2026

What is CVE-2026-33586?

Authenticated users of OVH mail servers can exploit a vulnerability to manipulate email header fields, specifically the 'Envelope-from' and 'From' fields. This manipulation allows users to send emails that appear to originate from any domain hosted by OVH. Due to the default SPF configuration that includes mx.ovh.com, these spoofed emails can bypass SPF validation, posing a significant risk of fraud and phishing attacks, as the true sender can misrepresent themselves using any OVH-hosted domain.

Affected Version(s)

OVHcloud 0 < 2026-07-20

References

https://docs.ovhcloud.com/en/guides/web-cloud/email-and-c...

CVSS V4

Score:
6.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Abdullah HAMED of ENGIE IT Offensive Cybersecurity Team
.