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FKIE_CVE-2026-28753

Vulnerability from fkie_nvd - Published: 2026-03-24 15:16 - Updated: 2026-06-17 10:28
Severity
3.7 (Low) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Summary
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
References
f5sirt@f5.comhttps://my.f5.com/manage/s/article/K000160367Vendor Advisory
Impacted products
Vendor Product Version
f5 nginx_plus r32
f5 nginx_plus r32
f5 nginx_plus r32
f5 nginx_plus r32
f5 nginx_plus r33
f5 nginx_plus r33
f5 nginx_plus r33
f5 nginx_plus r33
f5 nginx_plus r34
f5 nginx_plus r34
f5 nginx_plus r34
f5 nginx_plus r35
f5 nginx_plus r35
f5 nginx_plus r36
f5 nginx_plus r36
f5 nginx_plus r36
f5 nginx_open_source *
f5 nginx_open_source *
f5 nginx_open_source *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unknown",
          "modules": [
            "ngx_mail_proxy_module"
          ],
          "product": "NGINX Open Source",
          "vendor": "F5",
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              "status": "affected",
              "version": "1.29.0",
              "versionType": "semver"
            },
            {
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              "status": "affected",
              "version": "0.6.27",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "unknown",
          "modules": [
            "ngx_mail_proxy_module"
          ],
          "product": "NGINX Plus",
          "vendor": "F5",
          "versions": [
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              "lessThan": "R36 P3",
              "status": "affected",
              "version": "R36",
              "versionType": "custom"
            },
            {
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              "status": "affected",
              "version": "R35",
              "versionType": "custom"
            },
            {
              "lessThan": "*",
              "status": "affected",
              "version": "R34",
              "versionType": "custom"
            },
            {
              "lessThan": "*",
              "status": "affected",
              "version": "R33",
              "versionType": "custom"
            },
            {
              "lessThan": "R32 P5",
              "status": "affected",
              "version": "R32",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "f5sirt@f5.com"
    }
  ],
  "configurations": [
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              "vulnerable": true
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      ]
    },
    {
      "nodes": [
        {
          "cpeMatch": [
            {
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              "matchCriteriaId": "DAFF8985-B90A-4E7F-8EB6-7DBD9779CEE6",
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      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated."
    },
    {
      "lang": "es",
      "value": "NGINX Plus y NGINX Open Source tienen una vulnerabilidad en el m\u00f3dulo ngx_mail_smtp_module debido al manejo inadecuado de secuencias CRLF en las respuestas DNS. Esto permite a un servidor DNS controlado por el atacante inyectar encabezados arbitrarios en las solicitudes upstream SMTP, lo que lleva a una posible manipulaci\u00f3n de solicitudes. Nota: Las versiones de software que han alcanzado el Fin de Soporte T\u00e9cnico (EoTS) no son evaluadas."
    }
  ],
  "id": "CVE-2026-28753",
  "lastModified": "2026-06-17T10:28:59.190",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 3.7,
          "baseSeverity": "LOW",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 1.4,
        "source": "f5sirt@f5.com",
        "type": "Secondary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "HIGH",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.3,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/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",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "LOW",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "f5sirt@f5.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-28753",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-03-24T15:24:28.689685Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-03-24T15:16:33.560",
  "references": [
    {
      "source": "f5sirt@f5.com",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://my.f5.com/manage/s/article/K000160367"
    }
  ],
  "sourceIdentifier": "f5sirt@f5.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-93"
        }
      ],
      "source": "f5sirt@f5.com",
      "type": "Secondary"
    }
  ]
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.


Detection rules are retrieved from Rulezet.


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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.