CVE-2021-31840
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 · uneditedA vulnerability in the preloading mechanism of specific dynamic link libraries in McAfee Agent for Windows prior to 5.7.3 could allow an authenticated, local attacker to perform a DLL preloading attack with unsigned DLLs. To exploit this vulnerability, the attacker would need to have valid credentials on the Windows system. This would result in the user gaining elevated permissions and being able to execute arbitrary code.
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 confidenceMcAfee Agent for Windows prior to version 5.7.3 contains a DLL preloading vulnerability where the application insecurely loads dynamic link libraries without validating the DLL path or signature. An authenticated local attacker can place a malicious unsigned DLL in a location where the application searches for DLLs, causing arbitrary code execution with elevated privileges.
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>= 5.0.0, < 5.7.3CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/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 checksWork through these to decide whether this CVE applies to you.
-
Find installed McAfee Agent versionOpen Windows PowerShell and run: Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*' | Where-Object {$_.DisplayName -like '*McAfee Agent*'} | Select-Object DisplayName, DisplayVersion. Alternatively, right-click the McTray.exe or McScript.exe file in the McAfee Agent installation directory (commonly C:\Program Files\McAfee\Agent\ or C:\Program Files (x86)\McAfee\Agent\), select Properties, and view the Version tab.Affected if The displayed version is 5.0.0 through 5.7.2 (any version >= 5.0.0 but < 5.7.3)
-
Identify McAfee Agent executable locationsCheck the installation directory where McAfee Agent binaries are stored. Common paths are C:\Program Files\McAfee\Agent\ or C:\Program Files (x86)\McAfee\Agent\. Look for executables such as McTray.exe, McScript.exe, or cmdagent.exe.Affected if The executables exist in a directory writable by non-admin users (standard user or low-privilege account)
-
Verify DLL search path accessibilityRun icacls.exe against the McAfee Agent installation directory. Example: icacls 'C:\Program Files\McAfee\Agent' or icacls 'C:\Program Files (x86)\McAfee\Agent'. Review the output for permissions granted to Users, Authenticated Users, or other non-privileged groups.Affected if Users or Authenticated Users have Write (W) or Create Files (FA) permissions on the McAfee Agent directory or any subdirectory in its DLL search path
You are affected if McAfee Agent version is 5.0.0 through 5.7.2 AND non-privileged users can write files to directories where the application searches for DLLs.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor data5.7.3
Upgrade McAfee Agent for Windows to version 5.7.3 or later which addresses the insecure DLL preloading behavior. Additionally, restrict file system permissions to prevent unauthorized users from writing to directories in the DLL search path.
- Consultation2.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,480.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-31840 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-31840 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
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.
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.
- 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