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CVE-2026-3889

Status: ModifiedMedium (6.5)—

Spoofing issue in Thunderbird. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

Mozilla — Thunderbird

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2026-3889",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-3889",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-03-25T19:05:32.416050Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 6.5,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 2.8
      }
    ]
  },
  "affected": [
    {
      "source": "security@mozilla.org",
      "affectedData": [
        {
          "vendor": "Mozilla",
          "product": "Thunderbird",
          "versions": [
            {
              "status": "unaffected",
              "version": "140.9",
              "versionType": "rpm",
              "lessThanOrEqual": "140.*"
            },
            {
              "status": "unaffected",
              "version": "149",
              "versionType": "rpm",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-03-24T21:16:29.330",
  "references": [
    {
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2020723",
      "tags": [
        "Permissions Required"
      ],
      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-23/",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-24/",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "security@mozilla.org"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "description": [
        {
          "lang": "en",
          "value": "CWE-451"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Spoofing issue in Thunderbird. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9."
    },
    {
      "lang": "es",
      "value": "Problema de suplantación en Thunderbird. Esta vulnerabilidad afecta a Thunderbird < 149 y Thunderbird < 140.9."
    }
  ],
  "lastModified": "2026-06-17T10:44:23.140",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "4C0558B1-4113-45A8-8E37-A0793A67AD6D",
              "versionEndExcluding": "140.9.0"
            },
            {
              "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "40FE4697-89F1-46F6-8E28-41883647583B",
              "versionEndExcluding": "149.0"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "security@mozilla.org"
}