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Fencer Intel
high 8.8

CVE-2026-80302 json

Avast sandbox escape via arbitrary file write in virtualized environment

published 5d ago modified yesterday also EUVD-2026-118330

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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.

Patch / fix

  • Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate 26.7
  • Gen Digital AVG Antivirus Free, AVG Internet Security, AVG Ultimate 26.7
  • Gen Digital Norton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced 26.7

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
yesterday

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CISA ADP 3.1 8.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CNA 3.1 8.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected products

  • 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

Classification

Weakness
  • CWE-434 Unrestricted Upload of File with Dangerous Type
  • CWE-653 Improper Isolation or Compartmentalization

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.