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Internet SecurityApplication · Avira

CVE-2026-27750

HIGH · 7.0 CVSS v3.1 Published 2026-03-05
Fix available
A fix is available. Upgrade to 1.1.114.3113 or later.
See remediation →
72/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Avira Internet Security Optimizer has a TOCTOU vulnerability where a privileged SYSTEM service scans for directories to clean, then later deletes them without revalidating the path. A local attacker can replace a scanned directory with a junction/reparse point before the cleanup phase, causing the privileged process to delete unintended system locations.

MitigationImplement atomic path validation and revalidation immediately before deletion operations to verify the target path has not been modified. Use Windows APIs that atomically resolve junction points and validate paths within the same transaction as deletion.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Internet SecurityApplication
Affected:< 1.1.114.3113

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
High
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify Avira Internet Security installation
    Check for Avira Internet Security in Programs and Features or list installed programs via registry: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{ProductCode} or check C:\Program Files\Avira directory
    Affected if Avira Internet Security is installed on the system
  2. Determine installed version of Avira Internet Security
    Open Avira client, go to Help > About, or check registry key HKLM\SOFTWARE\Avira\Setup\Instance1\Version to retrieve the exact version number
    Affected if The installed version is lower than 1.1.114.3113
  3. Confirm Optimizer component is present
    Check for Avira Optimizer executable at C:\Program Files\Avira\Optimizer or look for Avira.Optimizer.Service.exe in task manager services
    Affected if The Optimizer service component is present on the system
  4. Verify SYSTEM-level privilege of Avira services
    Open Services.msc, locate Avira services, right-click and check Properties > Log On tab, or run 'sc queryex' for Avira services to confirm they run under the LocalSystem account
    Affected if Avira Optimizer service runs under the LocalSystem (SYSTEM) account

You are affected if Avira Internet Security with version lower than 1.1.114.3113 is installed and the Optimizer component, running with SYSTEM privileges, is present on your system.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.1.114.3113 or later
Fixed in 1.1.114.3113
Interim mitigation

Implement atomic path validation and revalidation immediately before deletion operations to verify the target path has not been modified. Use Windows APIs that atomically resolve junction points and validate paths within the same transaction as deletion.

Recommended fix High confidence

1.1.114.3113 or later

  1. 1. Open the Avira Internet Security application on the affected system
  2. 2. Navigate to the settings or help section of the application
  3. 3. Check the current installed version under 'About' or 'Version Information'
  4. 4. If the version is below 1.1.114.3113, initiate an update check or navigate to the update settings
  5. 5. Download and install the latest version (1.1.114.3113 or later) from the official Avira download page at www.avira.com
  6. 6. Alternatively, use the built-in update mechanism: Help > Check for Updates
  7. 7. After installation, verify the version number matches 1.1.114.3113 or higher
  8. 8. Restart the system to ensure all optimizer components are properly loaded

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Internet Security Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing10.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,580
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-27750 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data