CVE-2025-14098: Avira Antivirus Engine Heap Buffer Overflow—Patch Guidance

Technical summary

CVE-2025-14098 is a heap buffer out-of-bounds write vulnerability (CWE-787) caused by an integer overflow (CWE-190) in the Avira Antivirus engine's MS-DOS executable parsing logic. When the engine processes a malformed MS-DOS header or embedded structures, an integer calculation fails to prevent heap memory corruption. The vulnerability requires user interaction—specifically, the user must initiate a scan of the malicious file—but does not require elevated privileges. The flaw affects Avira Antivirus engine versions prior to 8.3.70.104 across all supported operating systems.

Business impact

A successful exploit could allow an attacker to execute arbitrary code on an infected system with the privileges of the antivirus process, potentially enabling lateral movement, data exfiltration, or further system compromise. Alternatively, the vulnerability could be weaponized for denial-of-service attacks against the antivirus engine itself, disabling real-time protection and leaving systems undefended. For organizations relying on Avira for endpoint protection, this represents a direct threat to the security infrastructure designed to protect against other threats.

Affected systems

All installations of Avira Antivirus running engine builds earlier than 8.3.70.104 are vulnerable. This includes deployments on Windows, macOS, and Linux. Both consumer and enterprise versions are affected if they use vulnerable engine versions. Organizations with version tracking or automated patching may already have remediated this issue; those with manual patching processes or pinned versions require immediate attention.

Exploitability

The vulnerability requires local access and user interaction to exploit. An attacker must either convince a user to scan a malicious file or place the malformed executable in a location that triggers automatic scanning. The CVSS vector (AV:L/AC:L/PR:N/UI:R) reflects local attack surface, low complexity, and required user interaction. While not remotely exploitable, the attack complexity is low because crafting a malformed MS-DOS file is trivial, and social engineering to prompt a manual scan is a proven technique. The high base score of 7.8 reflects the severe impact (code execution) despite the interaction requirement.

Remediation

Immediately update Avira Antivirus to engine version 8.3.70.104 or later. Consult the vendor's security advisory to verify the correct build numbers for your platform and product edition. For organizations with centralized deployment, use your management console to push updates to all endpoints. In the interim, disable real-time scanning if operationally feasible, though this creates significant risk exposure. Until patched, educate users to avoid scanning untrusted files from unknown sources.

Patch guidance

Verify the current engine version across your fleet using Avira's management tools or endpoint agent reporting. Prioritize patching all Windows, macOS, and Linux systems running versions before 8.3.70.104. Test the update in a non-production environment first to ensure compatibility with your security workflows and any custom scanning policies. After deployment, confirm engine version updates via agent telemetry or log analysis. Consider scheduling updates during maintenance windows to minimize user disruption, but do not delay patching due to the high severity of the vulnerability.

Detection guidance

Monitor for failed antivirus engine processes or unexpected restarts of the Avira service, which may indicate exploitation or denial-of-service attempts. Review Avira engine logs for parsing errors or out-of-memory conditions related to malformed executable processing. Endpoint detection and response (EDR) tools should flag processes spawned by or with unusual parent processes involving the antivirus engine. Hunt for suspicious MS-DOS executables or files with anomalous headers that may have been used in exploitation attempts. Correlate scanning activity logs with system events to identify the source file that triggered the crash or code execution.

Why prioritize this

This vulnerability merits immediate patching despite its requirement for user interaction. The impact is severe (code execution) on security infrastructure itself, potentially compromising downstream detection and response capabilities. The ease of crafting a trigger file and the prevalence of social engineering tactics lower the practical exploitation barrier. Organizations should treat this as critical and prioritize it ahead of vulnerabilities affecting less privileged processes, as compromise of the antivirus engine undermines the entire endpoint security posture.

Risk score, explained

The CVSS 3.1 score of 7.8 (HIGH) reflects high impact across confidentiality, integrity, and availability (C:H/I:H/A:H) balanced against the requirement for local access and user interaction. The score appropriately captures that this is not a worm or network-propagating threat, but once triggered, the damage is severe. The absence of a required privilege level (PR:N) acknowledges that any user can initiate the vulnerability by scanning a file. No scope change (S:U) is modeled because the antivirus process runs in the user's security context, not in a separate trust boundary. The score reflects industry consensus on the severity of code execution vulnerabilities in security tools.

Frequently asked questions