CVE-2026-33586

Authenticated SMTP Sender Address Forgery

Published Oct 7, 2026 CVSS 4.0 · 6.3 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Ovhcloud
Ovhcloud ovhcloud
Vendors & Products Ovhcloud
Ovhcloud ovhcloud
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Authenticated SMTP Sender Address Forgery
Weaknesses CWE-1188
CWE-290
CWE-346
References
Metrics cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N/E:A'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
ENISA
Published
Updated
Oct 7, 2026, 8:27 PM
Reserved
Mar 23, 2026, 12:53 PM
Status
Awaiting Analysis
Published
Oct 7, 2026, 4:17 PM
Modified
Oct 8, 2026, 9:33 PM