CVE-2026-80302

Avast sandbox escape via arbitrary file write in virtualized environment

Published Nov 6, 2026 CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed
Description
Insufficient isolation in the Avast sandbox file virtualization layer on Windows allows a local, low-privileged attacker executing inside the sandbox to write arbitrary files outside sandbox containment and execute code on the host.



The sandbox virtualizes file system operations by intercepting write requests to protected system directories. However, the virtualization implementation fails to properly validate write targets in certain edge cases, allowing writes to bypass the virtualization redirection and reach the actual host file system in protected locations.



An attacker can exploit this to overwrite executable files, system libraries, or startup configurations with arbitrary content, leading to code execution with host privileges on subsequent system operations or reboot.

Remediation

Vendor Solution

Gen Digital has released a fix in Avast, AVG, and Norton version 26.7 and later. The fix improves validation in the file virtualization layer to correctly identify protected directories and enforce write redirection in all code paths, preventing bypass of sandbox file isolation. Upgrade to version 26.7 or later to remediate this issue.

Tracking

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Advisories

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History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'}

Type Values Removed Values Added
Description Insufficient isolation in the Avast sandbox file virtualization layer on Windows allows a local, low-privileged attacker executing inside the sandbox to write arbitrary files outside sandbox containment and execute code on the host. The sandbox virtualizes file system operations by intercepting write requests to protected system directories. However, the virtualization implementation fails to properly validate write targets in certain edge cases, allowing writes to bypass the virtualization redirection and reach the actual host file system in protected locations. An attacker can exploit this to overwrite executable files, system libraries, or startup configurations with arbitrary content, leading to code execution with host privileges on subsequent system operations or reboot.
Title Avast sandbox escape via arbitrary file write in virtualized environment
Weaknesses CWE-434
CWE-653
References

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Weaknesses

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Status
PUBLISHED
Assigner
GEN
Published
Updated
Nov 10, 2026, 6:32 PM
Reserved
Aug 26, 2026, 8:11 AM
Status
Awaiting Analysis
Published
Nov 6, 2026, 4:18 PM
Modified
Nov 12, 2026, 10:09 PM