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

> A local attacker can exploit a TOCTOU race condition in Avira's Optimizer to delete protected system files, leading to privilege escalation or denial of service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Mar 2026
- **Updated:** 1 Apr 2026
- **Also known as:** GHSA-qfjh-mfrq-8j64

## What is CVE-2026-27750?

CVE-2026-27750 is a high-severity vulnerability in Gen Digital Inc. Avira Internet Security, published on 5 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2026-27750?

It affects 1 product.


Products: Avira Internet Security.

## How do I fix CVE-2026-27750?

No fix has been published for CVE-2026-27750 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-27750 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27750 exists.

## Other vulnerabilities in Gen Digital Inc. Avira Internet Security

- [CVE-2026-27748](https://insights.sbomify.com/CVE-2026-27748/): Avira Internet Security Arbitrary File Deletion via Improper Link Resolution (high 7.8)
- [CVE-2026-27749](https://insights.sbomify.com/CVE-2026-27749/): Avira Internet Security System Speedup Insecure Deserialization (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-27750 and fix it if it is affected.

What it is: CVE-2026-27750 is a high-severity vulnerability in Gen Digital Inc. Avira Internet Security, published on 5 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27750 exists.

Affected product: Gen Digital Inc. Avira Internet Security. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-27750/ (Markdown: https://insights.sbomify.com/CVE-2026-27750/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-27750
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27750
- OSV: https://osv.dev/vulnerability/CVE-2026-27750

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-27750/
Summaries are generated and may contain mistakes; the official description above is the record.