CVE-2025-3500
📋 TL;DR
An integer overflow vulnerability in Avast Antivirus for Windows allows attackers to escalate privileges on affected systems. This affects Avast Antivirus versions 25.1.981.6 through 25.2.x. Users running vulnerable versions are at risk of local privilege escalation attacks.
💻 Affected Systems
- Avast Antivirus
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise where an attacker gains SYSTEM/administrator privileges, enabling installation of malware, disabling security controls, and accessing all data on the system.
Likely Case
Local privilege escalation from a standard user account to administrator/SYSTEM level, allowing attackers to bypass security restrictions and maintain persistence.
If Mitigated
Limited impact if proper endpoint protection and least privilege principles are implemented, though the vulnerability still provides a foothold for attackers.
🎯 Exploit Status
Exploitation requires local access to the system and some technical knowledge of integer overflow exploitation techniques.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 25.3 or later
Vendor Advisory: https://www.gendigital.com/us/en/contact-us/security-advisories/
Restart Required: Yes
Instructions:
1. Open Avast Antivirus. 2. Navigate to Settings > Update > Program. 3. Click 'Update' to download and install version 25.3 or later. 4. Restart the computer when prompted.
🔧 Temporary Workarounds
Temporary Antivirus Disable
windowsTemporarily disable Avast Antivirus to prevent exploitation (not recommended for production)
Right-click Avast icon in system tray > Avast shields control > Disable for 10 minutes/1 hour/until computer restart
🧯 If You Can't Patch
- Implement strict least privilege policies to limit standard user account capabilities
- Deploy additional endpoint detection and response (EDR) solutions to monitor for privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check Avast version: Open Avast > Menu > About. If version is between 25.1.981.6 and 25.2.x, the system is vulnerable.Check Version:
Open Avast Antivirus, click Menu > AboutVerify Fix Applied:
Verify Avast version is 25.3 or later in About section and ensure no privilege escalation alerts in security logs.📡 Detection & Monitoring
Log Indicators:
- Unusual process creation with elevated privileges from Avast processes
- Access violations or memory corruption events in Avast logs
Network Indicators:
- Local privilege escalation typically doesn't generate network traffic
SIEM Query:
Process Creation where Parent Process Name contains 'avast' AND Integrity Level changed from Medium to High/System