All vulnerabilities
CVE-2026-33586

OVHcloud: Authenticated SMTP Sender Address Forgery

OVHcloud OVHcloud
Open in ThreatlineRecord JSON
CVSS
6.3Medium
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.14%Chance of exploitation activity in the next 30 days, higher than 2% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in2026-07-20Fixed versionCVE List
Published7 Oct 2026Updated 7 Oct 2026CVE List

What fixes it

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

Authenticated users are able to manipulate both the SMTP envelope “Envelope-from” and “From” fields when sending emails through OVH mail servers.

Due to OVH's default SPF configuration, which commonly includes include:mx.ovh.com, any authenticated user with a valid OVH email account can send messages that appear to originate from any OVH-hosted domains using the default SPF record. Since the SPF policy explicitly authorizes OVH mail servers (mx.ovh.com) to send mail on behalf of these domains, forged messages successfully pass SPF validation despite not being authorized by the impersonated domain owner.

Text from CVE List

Affected versions 1

  • OVHcloudaffected: all versions before 2026-07-20CVE List

References 1