CVE-2026-82964
HighCVSS 8.8Summary
Avast's sandbox minifilter driver (aswSnx.sys) on Windows has an improper preservation of permissions vulnerability, allowing a local, low-privileged attacker in the sandbox to escape file isolation and escalate to SYSTEM.
Risk Assessment
An attacker can gain full control of the system, steal NTLM password hashes, and execute code as SYSTEM, posing a severe security threat.
Recommendation
Install the latest Avast update that fixes the vulnerability. Additionally, restrict system access and apply the principle of least privilege.
Other vulnerabilities in Avast Antivirus
See all- CVE-2017-8308High
In Avast Antivirus before v17, an unprivileged user can mark an arbitrary process as Trusted from the perspective of the Avast product. This bypasses the Self-Defense feature of the product, opening a door to subsequent attack on many of its components.
- CVE-2017-8307Critical
In Avast Antivirus before v17, using the LPC interface API exposed by the AvastSVC.exe Windows service, it is possible to launch predefined binaries, or replace or delete arbitrary files. This vulnerability is exploitable by any unprivileged user when Avast Self-Defense is disabled.
- CVE-2020-20118Medium
A buffer overflow vulnerability in the aswSnx.sys driver of Avast AntiVirus before version 19.7 allows a local attacker to cause a denial of service (DoS) via a crafted request.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS