CVE-2020-9399

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-02-28 · updated 2026-06-17
Weakness: CWE-436

Description

The Avast AV parsing engine allows virus-detection bypass via a crafted ZIP archive. This affects versions before 12 definitions 200114-0 of Antivirus Pro, Antivirus Pro Plus, and Antivirus for Linux.

Affected products

Avast Antivirus For Linux: before 12.0 — fixed in 12.0
Avast Antivirus Pro: before 12.0 — fixed in 12.0
Avast Antivirus Pro Plus: before 12.0 — fixed in 12.0

How to fix

Upgrade to a fixed version: Avast Antivirus For Linux 12.0; Avast Antivirus Pro 12.0; Avast Antivirus Pro Plus 12.0. Check the vendor advisory for mitigations.

References

https://blog.zoller.lu/p/tzo-23-2020-avast-generic-archive.html
https://seclists.org/fulldisclosure/2020/Feb/35
https://blog.zoller.lu/p/tzo-23-2020-avast-generic-archive.html
https://seclists.org/fulldisclosure/2020/Feb/35

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