CVE Catalog

CVE-2026-33586

MediumCVSS 6.3
Published: Updated: Translated: NVD NIST

Summary

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.

Risk Assessment

The risk is that attackers can spoof any OVH-hosted domain, potentially leading to phishing, fraud, and domain reputation damage.

Recommendation

Implement additional email authentication mechanisms such as DKIM and DMARC, and monitor outbound emails for unusual patterns.

Related vulnerabilities

Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS