{"id":"CVE-2026-82964","published":"2026-09-16T15:17:55.837","lastModified":"2026-09-17T19:17:05.013","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.","cvssScore":8.8,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","cwes":["CWE-281","CWE-653","CWE-862"],"vendors":[],"products":[],"references":[{"url":"https://github.com/MSNightmare/PrettyPrague","tags":[]},{"url":"https://support.avast.com/en-us/article/Update-Antivirus","tags":[]},{"url":"https://support.avg.com/SupportArticleView?l=en&urlname=Update-AVG-Antivirus","tags":[]},{"url":"https://support.norton.com/sp/en/us/home/current/solutions/v20240108175512167","tags":[]},{"url":"https://www.gendigital.com/us/en/contact-us/security-advisories/","tags":[]},{"url":"https://x.com/msnightmare2000/status/2094106041046765752","tags":[]}],"exploitRefs":[{"url":"https://github.com/MSNightmare/PrettyPrague","tags":[]}],"hasPoc":true,"ai":null}