CVE-2025-7002: Avira Antivirus Heap Buffer Vulnerability – Local Code Execution & DoS Risk

Technical summary

CVE-2025-7002 is a heap buffer out-of-bounds read (CWE-125) in Avira's antivirus scanning engine. When the scanner processes a malformed PDF file, insufficient bounds checking permits reading from memory regions beyond the allocated heap buffer. Depending on what data resides in adjacent memory and the attacker's ability to shape that data, this can lead to information disclosure or, more critically, be chained with heap exploitation techniques to achieve code execution. The vulnerability requires user interaction (the PDF must be scanned) and local system access, making it most practical in scenarios where an attacker can deliver the malicious PDF to a target machine.

Business impact

For organizations relying on Avira Antivirus for endpoint protection, this vulnerability degrades security posture and operational continuity. Successful exploitation could allow attackers to bypass antivirus defenses, execute arbitrary code with the privileges of the antivirus process (often elevated), or crash the antivirus engine and leave systems unprotected during the downtime. In environments where Avira is a critical control layer, particularly on sensitive workstations or servers, this creates a window of opportunity for follow-on attacks. Remediation delays extend exposure.

Affected systems

All Avira Antivirus installations on Windows, macOS, and Linux platforms with engine versions before 8.3.70.68 are affected. This spans consumer, small business, and enterprise deployments of Avira's antivirus product line. Organizations should inventory Avira deployments and query the engine version number across their fleet to determine scope. The vendor has not specified whether all product editions (Free, Premium, Professional, etc.) are equally affected; verify with Avira's official advisory if your deployment mix includes multiple editions.

Exploitability

Exploitation requires delivery of a crafted PDF to a system where Avira Antivirus is active and will scan the file. No patch is required on the attacker side, making this straightforward to weaponize. However, the attack is constrained to local scope—the attacker cannot trigger it remotely without first placing the file on the target system. This limits opportunistic exploitation but makes targeted attacks feasible. The lack of KEV designation suggests no evidence of active exploitation in the wild as of the publication date, but heap buffer vulnerabilities in security software are known targets for advanced adversaries. Given the simplicity of crafting a malformed PDF, organizations should assume exploitation capability exists or will be developed.

Remediation

Update Avira Antivirus to engine version 8.3.70.68 or later. Avira typically bundles engine updates into product releases and delivers them via automatic update mechanisms. Verify that automatic updates are enabled in your Avira deployment. For managed or enterprise environments, consult Avira's patch management documentation to confirm the release vehicle and schedule updates accordingly. Until patched, enforce file-based controls to prevent suspicious PDFs from reaching systems where Avira is the primary defense, though this is a temporary measure, not a substitute for patching.

Patch guidance

1. Confirm your current Avira engine version across your estate (check via the Avira client UI or management console). 2. Enable automatic updates if not already active, or manually trigger an update check. 3. Verify engine version post-update to confirm 8.3.70.68 or later is installed. 4. Prioritize patching on high-value systems (user workstations, servers handling sensitive data) first. 5. Test patches in a non-production environment if your change control process requires it. 6. Document the patch date and version for audit purposes. Avira's support portal and release notes will provide the most current guidance on update channels and any caveats.

Detection guidance

Monitor Avira process logs and engine diagnostics for signs of scanner crashes or unexpected terminations when processing PDF files. Endpoint detection and response (EDR) tools can flag heap corruption or memory access violations originating from the Avira engine process. Look for failed scan events, especially those involving PDF files from untrusted sources. If available, enable verbose logging in Avira to capture engine exceptions. Network monitoring can identify unusual traffic patterns if code execution does occur post-exploitation, though detection of the initial buffer overflow may be difficult without deep memory inspection.

Why prioritize this

This vulnerability merits timely remediation due to its high CVSS score (7.8), local code execution potential, and the privileged context of antivirus software. While exploitation requires user interaction and file delivery, the ease of crafting a malformed PDF and the ubiquity of email and web-based file sharing make the attack surface substantial. Organizations that consider Avira a critical control should deprioritize this below active zero-day exploitation, but should treat it as a near-term patch priority—aim to deploy within 30 days for most environments, sooner for high-risk asset groups.

Risk score, explained

The CVSS 3.1 score of 7.8 (HIGH) reflects: Attack Vector Local (requires file on system), Attack Complexity Low (no special conditions), Privileges Required None (runs in user context), User Interaction Required (user or admin must scan the PDF), Scope Unchanged, Confidentiality Impact High (memory disclosure), Integrity Impact High (code execution possible), and Availability Impact High (DoS via crash). The score appropriately captures the threat when exploitation succeeds, though it does not heavily discount for the requirement that the malformed PDF must reach the target system. The 'High' severity is justified given antivirus software's trusted role.

Frequently asked questions