CVE-2025-9033

Vulnerability

A heap buffer out-of-bounds read vulnerability exists in the Avira Antivirus engine when scanning a specially crafted PDF file. This issue affects Avira Antivirus on Windows, macOS, and Linux for engine builds before version 8.3.70.76. The flaw is triggered during the scanning process of a malformed PDF document, leading to an unsafe read beyond the allocated heap buffer.

Exploitation

An attacker can exploit this vulnerability by delivering a malformed PDF file to the target system. No authentication or special privileges are required to trigger the scan; the file only needs to be scanned by the vulnerable Avira Antivirus engine (e.g., via on-access or on-demand scanning). The exact sequence involves the engine parsing the malformed PDF structure, which causes a heap buffer out-of-bounds read.

Impact

Successful exploitation can lead to either local code execution (with the privileges of the antivirus engine process, typically SYSTEM on Windows) or denial of service (crash of the engine process). The compromise affects the integrity, availability, and potentially confidentiality of the affected system.

Mitigation

Avira Antivirus engine build 8.3.70.76 and later contain the fix for this issue, as indicated by the vendor advisory [1]. Users should update to the latest engine version through the product's update mechanism. No workarounds are documented in the available references; keeping antivirus definitions and engine up to date is the recommended mitigation.