Gen Digital Avira Internet Security up to 1.1.109.1990 Optimizer toctou

Summaryinfo

A vulnerability identified as critical has been detected in Gen Digital Avira Internet Security up to 1.1.109.1990. This affects an unknown part of the component Optimizer. Performing a manipulation results in toctou. This vulnerability is reported as CVE-2026-27750. The attack requires a local approach. No exploit exists.

Detailsinfo

A vulnerability was found in Gen Digital Avira Internet Security up to 1.1.109.1990. It has been classified as critical. This affects some unknown functionality of the component Optimizer. The manipulation with an unknown input leads to a toctou vulnerability. CWE is classifying the issue as CWE-367. The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Avira Internet Security contains a time-of-check time-of-use (TOCTOU) vulnerability in the Optimizer component. A privileged service running as SYSTEM identifies directories for cleanup during a scan phase and subsequently deletes them during a separate cleanup phase without revalidating the target path. A local attacker can replace a previously scanned directory with a junction or reparse point before deletion occurs, causing the privileged process to delete an unintended system location. This may result in deletion of protected files or directories and can lead to local privilege escalation, denial of service, or system integrity compromise depending on the affected target.

The weakness was disclosed by Quarkslab. The advisory is shared at blog.quarkslab.com. This vulnerability is uniquely identified as CVE-2026-27750 since 02/23/2026. The exploitability is told to be easy. An attack has to be approached locally. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 03/13/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-0618). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

• Avira Internet Security Suite

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Vendor

• Gen Digital

Name

• Avira Internet Security

Version

• 1.1.109.1990

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

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Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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