CVE-2025-7018: Avira Antivirus Engine Denial-of-Service Vulnerability

Technical summary

CVE-2025-7018 is a null pointer dereference (CWE-476) in the Avira Antivirus scanning engine that occurs during processing of malformed PE (Portable Executable) files. The flaw allows an unauthenticated local user to cause a denial-of-service condition by supplying a crafted PE file to the scanner. No code execution or data disclosure is possible; the impact is limited to availability of the antivirus process itself. The vulnerability exists across multiple platforms due to shared engine code.

Business impact

This vulnerability creates a window of vulnerability on affected systems. While Avira's protection is offline due to the crashed engine process, malware or other threats could potentially be introduced without detection. In environments where Avira is a primary or sole endpoint protection mechanism, this DoS condition could interrupt security monitoring and response capabilities. Recovery typically requires manual restart of the antivirus service or reboot. Organizations should assess the prevalence of affected Avira versions in their environment and prioritize patching based on exposure to untrusted files.

Affected systems

All versions of Avira Antivirus on Windows, macOS, and Linux platforms with engine builds prior to 8.3.70.64 are affected. This includes both standalone and enterprise deployments. Check your current engine version in Avira's settings or management console to determine if your installation falls within the vulnerable range.

Exploitability

Exploitability is moderate in complexity but requires local user interaction. An attacker must convince a user to scan a malformed PE file, or the file must be present on a system where Avira's real-time scanner processes it automatically. This could occur through email attachment, drive-by download, or USB-based distribution. The attack requires no special privileges and produces a reliable denial-of-service condition, making it a viable griefing or disruption tactic against specific targets but unlikely to be leveraged in mass exploitation campaigns.

Remediation

Update Avira Antivirus to engine version 8.3.70.64 or later. Verify the engine version matches or exceeds this threshold across all affected systems. Avira typically delivers engine updates automatically through its update mechanism; check for pending updates and force a manual update if automatic delivery has not completed. For enterprise deployments, coordinate updates through your management console to ensure consistent patching.

Patch guidance

Obtain engine version 8.3.70.64 or later through Avira's official update channels. On Windows, check Settings > Update or use the Avira Control Center to trigger an immediate update check. On macOS and Linux, use the application menu or command-line update tools provided by Avira. Verify successful patching by confirming the engine version in antivirus settings reflects the patched build number. Test a sample malformed PE file (create a small file with PE header corruption) against the updated scanner to confirm normal operation without crashes. If automatic updates are blocked, consult Avira's documentation for manual engine distribution packages compatible with your platform.

Detection guidance

Monitor for antivirus process crashes or unexpected restarts of Avira services on Windows, macOS, and Linux systems. Check system logs and Avira's own logs for entries indicating scanner crashes or null pointer exceptions during file scanning. Enable verbose logging in Avira if available to capture details of problematic file scans. Correlate crash events with suspicious or unusual file activity preceding the crash time. In enterprise environments, use endpoint detection and response (EDR) tools or SIEM integration to alert on Avira process termination events. Consider deploying file integrity monitoring on systems where Avira is a critical control to detect whether the protection gap allowed unauthorized changes.

Why prioritize this

This vulnerability merits prompt but not emergency patching. The CVSS score of 5.5 (Medium) reflects the availability-only impact and local attack vector. However, the ease of triggering and the security monitoring gap it creates during exploitation justify prioritization above routine updates. Organizations running Avira as their primary endpoint protection should patch within 30 days. Environments with defense-in-depth (layered controls) and low exposure to untrusted file sources may defer to the next scheduled maintenance window, provided the exposure is documented.

Risk score, explained

The CVSS 3.1 score of 5.5 reflects a Medium severity rating due to several factors: the attack vector is Local (AV:L), meaning an attacker needs some level of system access or user interaction; the attack complexity is Low (AC:L), indicating the malformed file reliably triggers the crash; no privileges are required (PR:N) beyond the ability to place or scan a file; the scope is Unchanged (S:U); and the impact is High for Availability (A:H) but None for Confidentiality and Integrity (C:N, I:N). The result is a moderate risk that does not rise to 'High' or 'Critical' but warrants timely remediation.

Frequently asked questions