CVE-2017-5567: Avast Free Antivirus

Medium severity, CVSS 6.7. EPSS: 0.5% chance of exploitation in the next 30 days.

Code injection vulnerability in Avast Premier 12.3 (and earlier), Internet Security 12.3 (and earlier), Pro Antivirus 12.3 (and earlier), and Free Antivirus 12.3 (and earlier) allows a local attacker to bypass a self-protection mechanism, inject arbitrary code, and take full control of any Avast process via a "DoubleAgent" attack. One perspective on this issue is that (1) these products do not use the Protected Processes feature, and therefore an attacker can enter an arbitrary Application Verifier Provider DLL under Image File Execution Options in the registry; (2) the self-protection mechanism is intended to block all local processes (regardless of privileges) from modifying Image File Execution Options for these products; and (3) this mechanism can be bypassed by an attacker who temporarily renames Image File Execution Options during the attack.

Affected products

• Avast Free Antivirus: up to and including 12.3
• Avast Internet Security: up to and including 12.3
• Avast Premier: up to and including 12.3
• Avast Pro Antivirus: up to and including 12.3

Published 2017-03-21. Last modified 2026-06-17.