FKIE_CVE-2025-3909

Vulnerability from fkie_nvd - Published: 2025-05-14 17:15 - Updated: 2025-11-03 20:18
Severity ?
6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Summary
Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context. By crafting a nested email attachment (message/rfc822) and setting its content type to application/pdf, Thunderbird may incorrectly render it as HTML when opened, allowing the embedded JavaScript to run without requiring a file download. This behavior relies on Thunderbird auto-saving the attachment to /tmp and linking to it via the file:/// protocol, potentially enabling JavaScript execution as part of the HTML. This vulnerability affects Thunderbird < 128.10.1 and Thunderbird < 138.0.1.
References
security@mozilla.orghttps://bugzilla.mozilla.org/show_bug.cgi?id=1958376Permissions Required
security@mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2025-34/Vendor Advisory
security@mozilla.orghttps://www.mozilla.org/security/advisories/mfsa2025-35/Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2025/05/msg00022.html
Impacted products
Vendor Product Version
mozilla thunderbird *
mozilla thunderbird *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "82B93B43-AAD0-4F6F-8022-9842E39D73D6",
              "versionEndExcluding": "128.10.1",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "4AFE1A41-57DD-4532-9F3F-D3E9705868BA",
              "versionEndExcluding": "138.0.1",
              "versionStartIncluding": "129.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Thunderbird\u0027s handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context. By crafting a nested email attachment (message/rfc822) and setting its content type to application/pdf, Thunderbird may incorrectly render it as HTML when opened, allowing the embedded JavaScript to run without requiring a file download. This behavior relies on Thunderbird auto-saving the attachment to /tmp and linking to it via the file:/// protocol, potentially enabling JavaScript execution as part of the HTML. This vulnerability affects Thunderbird \u003c 128.10.1 and Thunderbird \u003c 138.0.1."
    },
    {
      "lang": "es",
      "value": "La gesti\u00f3n que Thunderbird hace del encabezado X-Mozilla-External-Attachment-URL puede explotarse para ejecutar JavaScript en el contexto file:///. Al manipular un archivo adjunto de correo electr\u00f3nico anidado (message/rfc822) y configurar su tipo de contenido como application/pdf, Thunderbird puede representarlo incorrectamente como HTML al abrirlo, lo que permite que el JavaScript incrustado se ejecute sin necesidad de descargar el archivo. Este comportamiento se basa en que Thunderbird guarda autom\u00e1ticamente el archivo adjunto en /tmp y lo enlaza mediante el protocolo file:///, lo que podr\u00eda permitir la ejecuci\u00f3n de JavaScript como parte del HTML. Esta vulnerabilidad afecta a Thunderbird versiones anteriores a la 128.10.1 y a la 138.0.1."
    }
  ],
  "id": "CVE-2025-3909",
  "lastModified": "2025-11-03T20:18:48.220",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 2.5,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ]
  },
  "published": "2025-05-14T17:15:48.660",
  "references": [
    {
      "source": "security@mozilla.org",
      "tags": [
        "Permissions Required"
      ],
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1958376"
    },
    {
      "source": "security@mozilla.org",
      "tags": [
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      "url": "https://www.mozilla.org/security/advisories/mfsa2025-34/"
    },
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      "source": "security@mozilla.org",
      "tags": [
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      "url": "https://www.mozilla.org/security/advisories/mfsa2025-35/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00022.html"
    }
  ],
  "sourceIdentifier": "security@mozilla.org",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-290"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}


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