Vulnerability-Lookup

GHSA-RPC3-43RH-HPM4

Vulnerability from github – Published: 2026-10-07 18:32 – Updated: 2026-10-07 18:32

Details

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.

Severity

6.3 (Medium)


                  
                    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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-33586"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-290"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-07T16:17:47Z",
    "severity": "MODERATE"
  },
  "details": "Authenticated users are able to manipulate both the SMTP\nenvelope \u201cEnvelope-from\u201d and \u201cFrom\u201d fields when sending\nemails through OVH mail servers.\n\n\n\nDue to OVH\u0027s default SPF configuration, which\ncommonly includes include:mx.ovh.com, any authenticated user with a\nvalid OVH email account can send messages that appear to originate from any\nOVH-hosted domains using the default SPF record. Since the SPF policy\nexplicitly authorizes OVH mail servers (mx.ovh.com) to send mail on behalf of\nthese domains, forged messages successfully pass SPF validation despite\nnot being authorized by the impersonated domain owner.",
  "id": "GHSA-rpc3-43rh-hpm4",
  "modified": "2026-10-07T18:32:09Z",
  "published": "2026-10-07T18:32:09Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33586"
    },
    {
      "type": "WEB",
      "url": "https://docs.ovhcloud.com/en/guides/web-cloud/email-and-collaborative-solutions/troubleshooting/email-rejected-cross-domain-spoofing"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-33586 (GCVE-0-2026-33586)

Vulnerability from cvelistv5 – Published: 2026-10-07 15:00 – Updated: 2026-10-07 20:27

Title

Authenticated SMTP Sender Address Forgery

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.

Severity

6.3 (Medium)


                        
                          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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-07 20:27 UTC

CWE

CWE-1188 - Initialization of a resource with an insecure default
CWE-346 - Origin Validation Error
CWE-290 - Authentication bypass by spoofing

Assigner

ENISA ENISA root Scorecard

References

1 reference

URL	Tags
https://docs.ovhcloud.com/en/guides/web-cloud/ema…

Impacted products

1 product

Vendor	Product	Version
OVHcloud	OVHcloud	Affected: 0 , < 2026-07-20 (date)

Credits

Abdullah HAMED of ENGIE IT Offensive Cybersecurity Team

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-33586",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-07T20:27:35.754415Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-07T20:27:49.038Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "OVHcloud",
          "vendor": "OVHcloud",
          "versions": [
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              "lessThan": "2026-07-20",
              "status": "affected",
              "version": "0",
              "versionType": "date"
            }
          ]
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      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Abdullah HAMED of ENGIE IT Offensive Cybersecurity Team"
        }
      ],
      "descriptions": [
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          "supportingMedia": [
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              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eAuthenticated users are able to manipulate both the SMTP\nenvelope \u201cEnvelope-from\u201d and \u201cFrom\u201d fields when sending\nemails through OVH mail servers.\u003c/p\u003e\u003cp\u003eDue to OVH\u0027s default SPF configuration, which\ncommonly includes include:mx.ovh.com, any authenticated user with a\nvalid OVH email account can send messages that appear to originate from any\nOVH-hosted domains using the default SPF record. Since the SPF policy\nexplicitly authorizes OVH mail servers (mx.ovh.com) to send mail on behalf of\nthese domains, forged messages successfully pass SPF validation despite\nnot being authorized by the impersonated domain owner.\u003c/p\u003e\u003cbr\u003e"
            }
          ],
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        }
      ],
      "metrics": [
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            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
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            "exploitMaturity": "ATTACKED",
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            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
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            "vulnerabilityResponseEffort": "NOT_DEFINED"
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          "scenarios": [
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          "descriptions": [
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              "cweId": "CWE-346",
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              "lang": "en",
              "type": "CWE"
            }
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        },
        {
          "descriptions": [
            {
              "cweId": "CWE-290",
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              "lang": "en",
              "type": "CWE"
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      "providerMetadata": {
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      "references": [
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          "url": "https://docs.ovhcloud.com/en/guides/web-cloud/email-and-collaborative-solutions/troubleshooting/email-rejected-cross-domain-spoofing"
        }
      ],
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    "datePublished": "2026-10-07T15:00:14.278Z",
    "dateReserved": "2026-03-23T12:53:47.473Z",
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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GHSA-RPC3-43RH-HPM4

CVE-2026-33586 (GCVE-0-2026-33586)

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