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CVE-2026-6774

Status: AnalyzedMedium (5.4)—

Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.

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 (2)

Mozilla — FirefoxMozilla — Thunderbird

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2026-6774",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-6774",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-04-21T14:01:03.413146Z"
        }
      }
    ],
    "cvssMetricV31": [
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        "type": "Secondary",
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        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
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          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "LOW"
        },
        "impactScore": 2.7,
        "exploitabilityScore": 2.3
      }
    ]
  },
  "affected": [
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      "source": "security@mozilla.org",
      "affectedData": [
        {
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          "product": "Firefox",
          "versions": [
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          "product": "Thunderbird",
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              "versionType": "rpm",
              "lessThanOrEqual": "*"
            }
          ]
        }
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    }
  ],
  "published": "2026-04-21T13:16:23.173",
  "references": [
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      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2016915",
      "tags": [
        "Permissions Required"
      ],
      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-30/",
      "tags": [
        "Vendor Advisory"
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      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-33/",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "security@mozilla.org"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
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      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "description": [
        {
          "lang": "en",
          "value": "CWE-693"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 150 and Thunderbird 150."
    }
  ],
  "lastModified": "2026-06-17T11:01:18.853",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
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  "sourceIdentifier": "security@mozilla.org"
}