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CVE-2026-109705

Status: DeferredCritical (9.6)—

Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

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).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

Vector AV:N/PR:N/UI:R exige interacción del usuario; el texto cita sandbox escape y use-after-free, pero no detalla comandos ejecutados, por lo que la confianza en T1059 es moderada.

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Application Isolation and SandboxingExploit ProtectionUpdate Software

Affected technologies (2)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Mozilla — FirefoxAIMozilla — Firefox ESRAI

CWEs

References

Raw JSON (NVD)

Show
{
  "id": "CVE-2026-109705",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-109705",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-10-13T14:14:35.331154Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 9.6,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 6,
        "exploitabilityScore": 2.8
      }
    ]
  },
  "affected": [
    {
      "source": "security@mozilla.org",
      "affectedData": [
        {
          "vendor": "Mozilla",
          "product": "Firefox",
          "versions": [
            {
              "status": "unaffected",
              "version": "153.5",
              "versionType": "rpm",
              "lessThanOrEqual": "153.*"
            },
            {
              "status": "unaffected",
              "version": "158",
              "versionType": "rpm",
              "lessThanOrEqual": "*"
            }
          ]
        },
        {
          "vendor": "Mozilla",
          "product": "Thunderbird",
          "versions": [
            {
              "status": "unaffected",
              "version": "153.5",
              "versionType": "rpm",
              "lessThanOrEqual": "153.*"
            },
            {
              "status": "unaffected",
              "version": "158",
              "versionType": "rpm",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-10-13T13:17:20.587",
  "references": [
    {
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2040905",
      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-106/",
      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-108/",
      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-109/",
      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-110/",
      "source": "security@mozilla.org"
    }
  ],
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5."
    }
  ],
  "lastModified": "2026-10-13T19:18:33.667",
  "sourceIdentifier": "security@mozilla.org"
}