CVE-2021-28826
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 Windows Installation component of TIBCO Software Inc.'s TIBCO Messaging - Eclipse Mosquitto Distribution - Bridge - Community Edition and TIBCO Messaging - Eclipse Mosquitto Distribution - Bridge - Enterprise Edition contains a vulnerability that theoretically allows a low privileged attacker with local access on some versions of the Windows operating system to insert malicious software. The affected component can be abused to execute the malicious software inserted by the attacker with the elevated privileges of the component. This vulnerability results from a lack of access restrictions on certain files and/or folders in the installation. Affected releases are TIBCO Software Inc.'s TIBCO Messaging - Eclipse Mosquitto Distribution - Bridge - Community Edition: versions 1.3.0 and below and TIBCO Messaging - Eclipse Mosquitto Distribution - Bridge - Enterprise Edition: versions 1.3.0 and below.
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 confidenceA local privilege escalation vulnerability exists in the Windows Installation component of TIBCO Messaging Eclipse Mosquitto Distribution (Community and Enterprise Edition versions 1.3.0 and below). The issue stems from insufficient access restrictions on certain files and folders within the installation directory, allowing a low-privileged local attacker to insert malicious software that subsequently executes 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<= 1.3.0CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify Mosquitto installation and versionCheck installed programs in Windows Control Panel > Programs and Features, or use PowerShell: Get-ItemProperty 'HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*' | Select-Object DisplayName, DisplayVersion | Where-Object {$_.DisplayName -like '*Mosquitto*'}. Alternatively, locate mosquitto.exe in the installation directory and right-click > Properties > Details to view the File Version.Affected if The installed version is 1.3.0 or lower, or the version cannot be determined but matches the product name 'TIBCO Messaging Eclipse Mosquitto Distribution'.
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Confirm Windows platformVerify the operating system is Windows. This vulnerability affects only the Windows installation component. Run 'systeminfo | findstr /B /C:"OS Name"' or check system properties.Affected if The target system is Windows and has Mosquitto installed.
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Locate installation directoryFind the Mosquitto installation path. Common default locations: C:\Program Files\TIBCO\Mosquitto\ or C:\Program Files (x86)\TIBCO\Mosquitto\. If installed via MSI, query the registry: Get-ItemProperty 'HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*' | Where-Object {$_.DisplayName -like '*Mosquitto*'} | Select-Object InstallLocation.Affected if An installation directory exists and contains Mosquitto files.
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Inspect folder access permissionsRight-click the installation folder (e.g., C:\Program Files\TIBCO\Mosquitto\) > Properties > Security tab. Verify which users and groups have permission to Modify or Write to this folder. Alternatively, run in PowerShell: Get-Acl 'C:\Program Files\TIBCO\Mosquitto\' | Select-Object -ExpandProperty AccessAffected if Non-privileged users (such as Users group or authenticated users) have Modify, Write, or Full Control permissions on the installation directory, allowing them to replace executable files.
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Check for World-writable subfoldersExamine subdirectories within the installation folder, particularly bin\, conf\, or lib\ folders. Use PowerShell: Get-ChildItem 'C:\Program Files\TIBCO\Mosquitto\' -Recurse | Get-Acl | Where-Object {$_.Access | Where-Object {$_.IdentityReference -like '*Users*' -and $_.FileSystemRights -like '*Write*'}}Affected if Any subfolder within the installation directory is writable by low-privileged users, enabling file injection.
A user is affected if TIBCO Messaging Eclipse Mosquitto Distribution version 1.3.0 or lower is installed on Windows and the installation directory or its subfolders grant Write or Modify permissions to non-administrative users.
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 dataUpgrade to a version above 1.3.0, or implement strict access control lists (ACLs) on installation directories to prevent modification by non-privileged users.
- Consultation3.0 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-2021-28826 — 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-2021-28826 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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