{"id":"CVE-2026-82964","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-82964","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…","details":"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.","published":"2026-09-16T15:17:55.837","modified":"2026-09-16T15:17:55.837","cvss":{"score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":null,"references":[{"type":"WEB","url":"https://github.com/MSNightmare/PrettyPrague"},{"type":"WEB","url":"https://support.avast.com/en-us/article/Update-Antivirus"},{"type":"WEB","url":"https://support.avg.com/SupportArticleView?l=en&urlname=Update-AVG-Antivirus"},{"type":"WEB","url":"https://support.norton.com/sp/en/us/home/current/solutions/v20240108175512167"},{"type":"WEB","url":"https://www.gendigital.com/us/en/contact-us/security-advisories/"},{"type":"WEB","url":"https://x.com/msnightmare2000/status/2094106041046765752"}],"provenance":{"sources":["OSV.dev","NVD","FIRST.org (EPSS)"],"lastVerified":"2026-09-16T15:17:55.837"}}