EUVD-2025-200023

Comprehensive Technical Analysis of EUVD-2025-200023

1. Vulnerability Assessment and Severity Evaluation

The vulnerability described in EUVD-2025-200023 is a heap-based buffer overflow and out-of-bounds read issue in Avast Antivirus on macOS. This vulnerability can lead to local execution of code or denial-of-service (DoS) of the antivirus engine process when scanning a malformed file. The CVSS (Common Vulnerability Scoring System) base score of 9.0 indicates a critical severity level. The CVSS vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H breaks down as follows:

• AV:N - Attack Vector: Network
• AC:H - Attack Complexity: High
• PR:N - Privileges Required: None
• UI:N - User Interaction: None
• S:C - Scope: Changed
• C:H - Confidentiality Impact: High
• I:H - Integrity Impact: High
• A:H - Availability Impact: High

The high complexity (AC:H) suggests that exploiting this vulnerability requires specialized conditions or knowledge, but the potential impact is severe, affecting confidentiality, integrity, and availability.

2. Potential Attack Vectors and Exploitation Methods

The primary attack vector is through network-based delivery of a malformed file designed to trigger the heap-based buffer overflow and out-of-bounds read. An attacker could exploit this vulnerability by:

• Phishing Emails: Sending malicious files via email attachments.
• Malicious Websites: Hosting malformed files on compromised or malicious websites.
• File Sharing: Distributing malformed files through peer-to-peer networks or cloud storage services.

Exploitation methods could involve crafting a file that, when scanned by the affected versions of Avast Antivirus, causes a buffer overflow leading to arbitrary code execution or a crash of the antivirus engine process.

3. Affected Systems and Software Versions

The vulnerability affects Avast Antivirus on macOS, specifically versions from 8.3.70.94 to 8.3.70.98. Users running these versions are at risk and should update to a patched version immediately.

4. Recommended Mitigation Strategies

To mitigate the risk associated with this vulnerability, the following strategies are recommended:

• Update Software: Ensure that all instances of Avast Antivirus are updated to version 8.3.70.98 or later.
• Network Security: Implement robust network security measures to detect and block malicious files.
• User Education: Educate users about the risks of opening files from unknown sources and the importance of keeping software updated.
• Intrusion Detection Systems (IDS): Deploy IDS to monitor for unusual activity that may indicate an exploitation attempt.
• Regular Audits: Conduct regular security audits to identify and address vulnerabilities in the software ecosystem.

5. Impact on European Cybersecurity Landscape

The vulnerability in Avast Antivirus, a widely used security software, poses a significant risk to the European cybersecurity landscape. Given the critical nature of antivirus software in protecting against malware and other threats, this vulnerability could be exploited to compromise the security of numerous systems across Europe. Organizations and individuals relying on Avast Antivirus must act swiftly to update their software to mitigate this risk.

6. Technical Details for Security Professionals

For security professionals, the following technical details are pertinent:

• Heap-based Buffer Overflow: This type of vulnerability occurs when a program writes more data to a buffer located in the heap than is actually allocated for that buffer. This can lead to overwriting adjacent memory, potentially allowing an attacker to execute arbitrary code.
• Out-of-bounds Read: This occurs when a program reads data from outside the bounds of allocated memory, which can lead to information disclosure or other unintended behavior.
• Exploitation: Crafting a malformed file that triggers the buffer overflow and out-of-bounds read requires detailed knowledge of the file format and the specific vulnerability.
• Detection: Security professionals should look for anomalies in memory usage and unexpected crashes of the antivirus engine process.
• Patch Analysis: Review the patch notes for version 8.3.70.98 to understand the specific changes made to address this vulnerability.

Conclusion

EUVD-2025-200023 represents a critical vulnerability in Avast Antivirus on macOS that requires immediate attention. By understanding the technical details, potential attack vectors, and mitigation strategies, cybersecurity professionals can effectively protect their systems and contribute to the overall security of the European cyber landscape.