CVE-2021-1492
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 · uneditedThe Duo Authentication Proxy installer prior to 5.2.1 did not properly validate file installation paths. This allows an attacker with local user privileges to coerce the installer to write to arbitrary privileged directories. If successful, an attacker can manipulate files used by Duo Authentication Proxy installer, cause Denial of Service (DoS) by deleting file(s), or replace system files to potentially achieve elevation of privileges. This is only exploitable during new installations, while the installer is running, and is not exploitable once installation has finished. Versions 5.2.1 of Duo Authentication Proxy installer addresses this issue.
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 confidenceThe Duo Authentication Proxy installer prior to version 5.2.1 contains a path traversal vulnerability that fails to properly validate file installation paths. An attacker with local user privileges can coerce the installer to write files to arbitrary privileged directories during the installation process, enabling file manipulation, DoS via file deletion, or system file replacement for potential privilege escalation.
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< 5.2.1CVSS 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
- None
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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.
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Check installed Duo Authentication Proxy versionOpen Windows Control Panel > Programs and Features, or run 'Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | Select-Object DisplayName, DisplayVersion' in PowerShell to find Duo Authentication Proxy entryAffected if The displayed version is lower than 5.2.1
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Verify installer was run recentlyCheck Windows Event Viewer under Windows Logs > Application for MSI installer events related to Duo Authentication Proxy, or check the installation log directory for recent installer activityAffected if An installation of Duo Authentication Proxy with version below 5.2.1 was performed recently on this system
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Inspect privileged directories for unexpected filesReview file creation timestamps in system directories such as C:\Windows\System32 and C:\ProgramData for files that appeared around the time of the Duo installer executionAffected if Unexpected or unexplained files exist in system directories with timestamps coinciding with the installation window
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Check for suspicious file modifications in startup locationsExamine C:\Users\*\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup and C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup for unauthorized executables or scriptsAffected if New executables or scripts appear in startup locations that were not intentionally installed by administrators
The system is affected if Duo Authentication Proxy version below 5.2.1 was installed, as the path traversal flaw could have allowed an attacker with local user privileges to place files in privileged directories during that installation.
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 data5.2.1
Upgrade to Duo Authentication Proxy installer version 5.2.1 or later which addresses the path validation issue. This is only exploitable during active installation, not after completion.
- Consultation2.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1492 — 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-2021-1492 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
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- Version or environment caveats, and links to real fixes
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