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CVE-2025-8040

Status: ModifiedHigh (8.8)—

Memory safety bugs present in Firefox ESR 140.0, Thunderbird ESR 140.0, Firefox 140 and Thunderbird 140. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 141, Firefox ESR 140.1, Thunderbird 141, and Thunderbird 140.1.

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 CVSS con UI:R (requiere interacción del usuario) indica explotación en cliente T1203. Memory safety bugs en navegador/correo permiten ejecución arbitraria de código T1059 tras corrupción de memoria.

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

Restrict Web-Based ContentPrivileged Account ManagementLimit Software InstallationExecution PreventionBehavior Prevention on EndpointDisable or Remove Feature or Program

Affected technologies (2)

Mozilla — FirefoxMozilla — Thunderbird

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2025-8040",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2025-8040",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2025-07-24T03:55:32.317082Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 8.8,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 2.8
      }
    ]
  },
  "affected": [
    {
      "source": "security@mozilla.org",
      "affectedData": [
        {
          "vendor": "Mozilla",
          "product": "Firefox",
          "versions": [
            {
              "status": "unaffected",
              "version": "140.1",
              "versionType": "rpm",
              "lessThanOrEqual": "140.*"
            },
            {
              "status": "unaffected",
              "version": "141",
              "versionType": "rpm",
              "lessThanOrEqual": "*"
            }
          ]
        },
        {
          "vendor": "Mozilla",
          "product": "Thunderbird",
          "versions": [
            {
              "status": "unaffected",
              "version": "140.1",
              "versionType": "rpm",
              "lessThanOrEqual": "140.*"
            },
            {
              "status": "unaffected",
              "version": "141",
              "versionType": "rpm",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  ],
  "published": "2025-07-22T21:15:51.163",
  "references": [
    {
      "url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=1975058%2C1975998",
      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2025-56/",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2025-59/",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2025-61/",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "security@mozilla.org"
    },
    {
      "url": "https://www.mozilla.org/security/advisories/mfsa2025-63/",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "security@mozilla.org"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "description": [
        {
          "lang": "en",
          "value": "CWE-119"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Memory safety bugs present in Firefox ESR 140.0, Thunderbird ESR 140.0, Firefox 140 and Thunderbird 140. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 141, Firefox ESR 140.1, Thunderbird 141, and Thunderbird 140.1."
    },
    {
      "lang": "es",
      "value": "Errores de seguridad de memoria presentes en Firefox ESR 140.0, Thunderbird ESR 140.0, Firefox 140 y Thunderbird 140. Algunos de estos errores mostraron evidencia de corrupción de memoria y presumimos que, con suficiente esfuerzo, algunos de ellos podrían haberse explotado para ejecutar código arbitrario. Esta vulnerabilidad afecta a Firefox menor que 141, Firefox ESR menor que 140.1, Thunderbird menor que 141 y Thunderbird menor que 140.1."
    }
  ],
  "lastModified": "2026-10-05T15:10:00.590",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
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              "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "260CDC56-79EC-44BF-9555-BB4321552203",
              "versionEndExcluding": "140.1"
            },
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              "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "8684A46E-D70A-4830-8971-A6DCC360F422",
              "versionEndExcluding": "141.0"
            },
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              "vulnerable": true,
              "matchCriteriaId": "99498D75-7441-458F-9C53-6ABCC7ED9AEC",
              "versionEndExcluding": "140.1"
            },
            {
              "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "95D506DD-BD9B-4D90-802F-5BE673F1CF14",
              "versionEndExcluding": "141.0"
            }
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  ],
  "sourceIdentifier": "security@mozilla.org"
}