dbcve.org
Internet SecurityApplication · Avira

CVE-2026-27749

HIGH · 7.8 CVSS v3.1 Published 2026-03-05
Fix available
A fix is available. Upgrade to 1.1.114.3113 or later.
See remediation →
80/100
Remediation priority · High
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 deserialization of untrusted data vulnerability in the System Speedup component. The Avira.SystemSpeedup.RealTimeOptimizer.exe process, which runs with SYSTEM privileges, deserializes data from a file located in C:\\ProgramData using .NET BinaryFormatter without implementing input validation or deserialization safeguards. Because the file can be created or modified by a local user in default configurations, an attacker can supply a crafted serialized payload that is deserialized by the privileged process, resulting in arbitrary code execution as SYSTEM.

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's System Speedup component (Avira.SystemSpeedup.RealTimeOptimizer.exe) runs with SYSTEM privileges and deserializes data from C:\ProgramData using .NET BinaryFormatter without input validation. A local unprivileged user can modify the target file to inject a crafted serialized payload, achieving arbitrary code execution as SYSTEM.

MitigationApply vendor patches when available; until then, disable or restrict the Avira.SystemSpeedup.RealTimeOptimizer.exe service and audit file permissions on C:\ProgramData to prevent unprivileged modification of the target file.

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
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/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 is installed
    Check for Avira Internet Security in Windows Registry under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall or look for Avira installation directory under C:\Program Files\Avira
    Affected if Avira Internet Security is not found, the system is not affected by this specific product
  2. Check installed version of Avira Internet Security
    Locate the installed version by checking the registry DisplayVersion value in the Avira uninstall key, or right-click the main Avira executable and view Properties > Details
    Affected if Version is less than 1.1.114.3113 - the system is running a vulnerable version
  3. Confirm presence of vulnerable component
    Verify Avira.SystemSpeedup.RealTimeOptimizer.exe exists in the Avira installation directory (typically C:\Program Files\Avira\System Speedup or similar)
    Affected if The executable is present - the deserialization component exists on the system
  4. Check if System Speedup service is configured or running
    Open Services.msc and look for an Avira System Speedup related service, or run 'sc query' to enumerate services containing 'Avira' and 'Speedup'
    Affected if The RealTimeOptimizer service is installed and enabled - the vulnerable code path can be triggered
  5. Audit file permissions on C:\ProgramData
    Right-click C:\ProgramData folder > Properties > Security tab, or use icacls C:\ProgramData to view which users have Write or Modify permissions
    Affected if Unprivileged users have Write or Modify access to C:\ProgramData - they can modify the target file that gets deserialized

A system is affected if it runs Avira Internet Security version below 1.1.114.3113 with the System Speedup component installed, and unprivileged users can write to C:\ProgramData where the service reads deserialized data.

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

Apply vendor patches when available; until then, disable or restrict the Avira.SystemSpeedup.RealTimeOptimizer.exe service and audit file permissions on C:\ProgramData to prevent unprivileged modification of the target file.

Recommended fix High confidence

Upgrade to version 1.1.114.3113 or later

  1. 1. Open Avira Internet Security application
  2. 2. Navigate to the settings or help section
  3. 3. Check the current version of Avira Internet Security
  4. 4. If the version is below 1.1.114.3113, initiate an update to obtain the latest version
  5. 5. Alternatively, download the latest version from the official Avira website (www.avira.com) or through the vendor's update mechanism
  6. 6. Ensure the update completes successfully
  7. 7. Verify the installed version is 1.1.114.3113 or higher

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

Fix this in Internet Security Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-27749 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2026-27749 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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