CVE-2026-82964 Avast sandbox privilege escalation via unpreserved DACLs on virtualized files in aswSnx.sys
A local attacker in the Avast sandbox can escape isolation and gain SYSTEM privileges due to improper DACL preservation in the aswSnx.sys driver.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-82964?
CVE-2026-82964 is a high-severity vulnerability in Gen Digital AVG Antivirus Free, AVG Internet Security, AVG Ultimate, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
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.
Which versions are affected by CVE-2026-82964?
How do I fix CVE-2026-82964?
No fix has been published for CVE-2026-82964 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-82964 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82964 exists.
Sources
Also known as GHSA-r5c7-vpw8-xf4v.