CVE-2021-34921
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 · uneditedThis vulnerability allows remote attackers to execute arbitrary code on affected installations of Bentley View 10.15.0.75. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the parsing of JT files. Crafted data in a JT file can trigger a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-14899.
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 buffer overflow vulnerability exists in Bentley View 10.15.0.75 during JT file parsing. When processing crafted JT files with specially formatted data, the parser writes past the end of an allocated buffer, allowing arbitrary code execution in the context of the current user process. User interaction is required (opening a malicious file or visiting a malicious page that loads a malicious JT).
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< 10.16.02< 10.16.02CVSS 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
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:N/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.
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Identify installed Bentley softwareCheck for Bentley View or Microstation installation by looking in Program Files for 'Bentley' folder, or check Windows Programs and Features listAffected if Either Bentley View or Microstation is present on the system
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Determine installed version of Bentley ViewOpen Bentley View, go to Help > About Bentley View, or right-click the executable in Program Files > Properties > Details to view the version numberAffected if Version is below 10.16.02 (e.g., 10.15.0.75 or any 10.x version prior to 10.16.02)
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Determine installed version of MicrostationOpen Microstation, go to Help > About Microstation, or right-click the executable in Program Files > Properties > Details to view the version numberAffected if Version is below 10.16.02
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Check if JT file handling is configuredOpen Bentley View or Microstation, go to File > Open and verify if .JT file type is listed in the supported formats, or check File > Settings > File > General for JT file associationsAffected if JT file type is available and enabled in the application, indicating the vulnerable parser can be triggered
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Review recent JT file accessCheck Windows Event Viewer for recent .JT file opens, or look at recent files list in Bentley applications, or check file association metadata in Windows registry under HKEY_CLASSES_ROOT for .JT extensionAffected if The system has recently opened or is configured to automatically open JT files, making user interaction with a malicious file possible
You are affected if either Bentley View or Microstation is installed with a version number less than 10.16.02 and JT file handling is enabled, as the buffer overflow vulnerability can be triggered when processing a malicious JT file.
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.
dbcve · scoped10.16.02
Update Bentley View to the latest patched version from Bentley's official channels. Until patched, avoid opening JT files from untrusted sources and disable file associations for JT files in untrusted contexts.
Bentley View 10.16.02 / Microstation 10.16.02
- Backup any important files and configurations before updating
- Navigate to the official Bentley website (www.bentley.com) and locate the download for Bentley View version 10.16.02 or later
- Navigate to the official Bentley website (www.bentley.com) and locate the download for Microstation version 10.16.02 or later
- Download the appropriate installer for your installed product (Bentley View or Microstation)
- Run the installer and follow the on-screen prompts to complete the upgrade
- Restart the application after installation completes
- Verify the version number shows 10.16.02 or later in the application's About section
- Test parsing of JT files to confirm the vulnerability is resolved
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 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-2021-34921 — 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-2021-34921 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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- 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
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