FKIE_CVE-2026-82964

Vulnerability from fkie_nvd - Published: 2026-09-16 15:17 - Updated: 2026-09-17 19:17
Severity
8.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Summary
Improper preservation of permissions in the Avast sandbox minifilter driver (aswSnx.sys) on Windows allows a local, low-privileged attacker executing inside the sandbox to escape file isolation and escalate to SYSTEM. When the sandbox virtualizes a file it copies the original security descriptor, but the driver opened the virtualization target object with GENERIC_WRITE and FILE_WRITE_ATTRIBUTES only, omitting WRITE_DAC. Every attempt to apply the original DACL therefore failed, and the failure was discarded silently, leaving virtualized copies of sensitive files with permissive permissions. Because the IRP_MJ_CREATE callback additionally did not strip WRITE_DAC for sensitive directories, a sandboxed process could rewrite the security descriptor of a virtualized object, read the virtualized copy of the SAM database, extract local NTLM password hashes and execute code as SYSTEM. The absence of an IRP_MJ_SET_SECURITY callback in the driver's operation registration table is a related defense-in-depth gap, but it is not the control that prevents this attack.
References
security@nortonlifelock.comhttps://github.com/MSNightmare/PrettyPrague
security@nortonlifelock.comhttps://support.avast.com/en-us/article/Update-Antivirus
security@nortonlifelock.comhttps://support.avg.com/SupportArticleView?l=en&urlname=Update-AVG-Antivirus
security@nortonlifelock.comhttps://support.norton.com/sp/en/us/home/current/solutions/v20240108175512167
security@nortonlifelock.comhttps://www.gendigital.com/us/en/contact-us/security-advisories/
security@nortonlifelock.comhttps://x.com/msnightmare2000/status/2094106041046765752
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "affected",
          "platforms": [
            "Windows"
          ],
          "product": "Avast Free Antivirus, Avast One, Avast Premium Security, Avast Ultimate, Avast Business Security",
          "vendor": "Gen Digital",
          "versions": [
            {
              "lessThan": "26.8",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "platforms": [
            "Windows"
          ],
          "product": "AVG Antivirus Free, AVG Internet Security, AVG Ultimate",
          "vendor": "Gen Digital",
          "versions": [
            {
              "lessThan": "26.8",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "platforms": [
            "Windows"
          ],
          "product": "Norton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced",
          "vendor": "Gen Digital",
          "versions": [
            {
              "lessThan": "26.8",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "security@nortonlifelock.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Improper preservation of permissions in the Avast sandbox minifilter driver (aswSnx.sys) on Windows allows a local, low-privileged attacker executing inside the sandbox to escape file isolation and escalate to SYSTEM.\n\n\n\nWhen the sandbox virtualizes a file it copies the original security descriptor, but the driver opened the virtualization target object with GENERIC_WRITE and FILE_WRITE_ATTRIBUTES only, omitting WRITE_DAC. Every attempt to apply the original DACL therefore failed, and the failure was discarded silently, leaving virtualized copies of sensitive files with permissive permissions. Because the IRP_MJ_CREATE callback additionally did not strip WRITE_DAC for sensitive directories, a sandboxed process could rewrite the security descriptor of a virtualized object, read the virtualized copy of the SAM database, extract local NTLM password hashes and execute code as SYSTEM.\n\n\n\nThe absence of an IRP_MJ_SET_SECURITY callback in the driver\u0027s operation registration table is a related defense-in-depth gap, but it is not the control that prevents this attack."
    }
  ],
  "id": "CVE-2026-82964",
  "lastModified": "2026-09-17T19:17:05.013",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.0,
        "impactScore": 6.0,
        "source": "security@nortonlifelock.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-82964",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-17T18:41:32.262077Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-16T15:17:55.837",
  "references": [
    {
      "source": "security@nortonlifelock.com",
      "url": "https://github.com/MSNightmare/PrettyPrague"
    },
    {
      "source": "security@nortonlifelock.com",
      "url": "https://support.avast.com/en-us/article/Update-Antivirus"
    },
    {
      "source": "security@nortonlifelock.com",
      "url": "https://support.avg.com/SupportArticleView?l=en\u0026urlname=Update-AVG-Antivirus"
    },
    {
      "source": "security@nortonlifelock.com",
      "url": "https://support.norton.com/sp/en/us/home/current/solutions/v20240108175512167"
    },
    {
      "source": "security@nortonlifelock.com",
      "url": "https://www.gendigital.com/us/en/contact-us/security-advisories/"
    },
    {
      "source": "security@nortonlifelock.com",
      "url": "https://x.com/msnightmare2000/status/2094106041046765752"
    }
  ],
  "sourceIdentifier": "security@nortonlifelock.com",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-281"
        },
        {
          "lang": "en",
          "value": "CWE-653"
        },
        {
          "lang": "en",
          "value": "CWE-862"
        }
      ],
      "source": "security@nortonlifelock.com",
      "type": "Secondary"
    }
  ]
}



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