{"id":"CVE-2026-82964","aliases":["EUVD-2026-80773","GHSA-r5c7-vpw8-xf4v"],"status":"published","title":"Avast sandbox privilege escalation via unpreserved DACLs on virtualized files in aswSnx.sys","description":"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's operation registration table is a related defense-in-depth gap, but it is not the control that prevents this attack.","severity":{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00157,"percentile":0.04906,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-281","CWE-653","CWE-862"],"published":"2026-09-16T14:01:47Z","modified":"2026-09-17T19:17:05Z","products":[{"vendor":"gen digital","product":"avast free antivirus, avast one, avast premium security, avast ultimate, avast business security"},{"vendor":"gen digital","product":"avg antivirus free, avg internet security, avg ultimate"},{"vendor":"gen digital","product":"norton antivirus plus, norton 360 standard, norton 360 deluxe, norton 360 advanced"}],"references":[{"url":"https://www.gendigital.com/us/en/contact-us/security-advisories/","tags":["vendor-advisory"]},{"url":"https://support.avast.com/en-us/article/Update-Antivirus","tags":["patch"]},{"url":"https://support.avg.com/SupportArticleView?l=en\u0026urlname=Update-AVG-Antivirus","tags":["patch"]},{"url":"https://support.norton.com/sp/en/us/home/current/solutions/v20240108175512167","tags":["patch"]},{"url":"https://github.com/MSNightmare/PrettyPrague","tags":["exploit"]},{"url":"https://x.com/msnightmare2000/status/2094106041046765752"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-82964"},{"url":"https://www.gendigital.com/us/en/contact-us/security-advisories"},{"url":"https://github.com/advisories/GHSA-r5c7-vpw8-xf4v"}],"sources":{"cve":[{"id":"CVE-2026-82964","title":"Avast sandbox privilege escalation via unpreserved DACLs on virtualized files in aswSnx.sys","description":"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's operation registration table is a related defense-in-depth gap, but it is not the control that prevents this attack.","status":"published","published":"2026-09-16T14:01:47.369Z","modified":"2026-09-17T18:42:28.924Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-281","CWE-653","CWE-862"],"updated_at":"2026-11-02T13:40:46.161838Z"}],"euvd":[{"id":"EUVD-2026-80773","description":"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's operation registration table is a related defense-in-depth gap, but it is not the control that prevents this attack.","status":"published","published":"2026-09-16T14:01:47Z","modified":"2026-09-17T18:42:28Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T17:28:10.38936Z"}],"ghsa":[{"id":"GHSA-r5c7-vpw8-xf4v","title":"Improper preservation of permissions in the Avast sandbox minifilter driver (aswSnx.sys) on...","description":"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's operation registration table is a related defense-in-depth gap, but it is not the control that prevents this attack.","status":"published","published":"2026-09-16T15:31:13Z","modified":"2026-09-16T15:31:21Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-281"],"updated_at":"2026-11-02T15:11:59.582427Z"}],"nvd":[{"id":"CVE-2026-82964","description":"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's operation registration table is a related defense-in-depth gap, but it is not the control that prevents this attack.","status":"published","published":"2026-09-16T15:17:55.837Z","modified":"2026-09-17T19:17:05.013Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-281","CWE-653","CWE-862"],"updated_at":"2026-11-02T14:12:48.630594Z"}]}}