CVE-2023-34303
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 · uneditedAshlar-Vellum Cobalt Out-Of-Bounds Read Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Ashlar-Vellum Cobalt. 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 VC6 files. The issue results from the lack of proper validation of user-supplied data, which can result in a read 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-17987.
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 · moderate confidenceAshlar-Vellum Cobalt contains an out-of-bounds read vulnerability in its VC6 file parser. The application fails to properly validate user-supplied data during VC6 file parsing, allowing an attacker to read past the end of an allocated buffer. This memory read primitive can be leveraged to achieve remote code execution in the context of the current process.
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= 11.0.1111CVSS 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:3.0/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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Verify Ashlar Cobalt is installedCheck for the presence of Ashlar Cobalt in the system. Common installation paths include C:\Program Files\Ashlar\ or C:\Program Files (x86)\Ashlar\ on Windows. Also check the Windows Registry under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall for an Ashlar Cobalt entry.Affected if Ashlar Cobalt software is found on the system
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Determine the installed Cobalt versionOpen the Cobalt application and navigate to Help > About, or check the Windows Registry at HKEY_LOCAL_MACHINE\SOFTWARE\Ashlar-Vellum\Cobalt for the Version value. The version number will appear as four dot-separated groups (e.g., 11.0.1111.XXXX).Affected if The installed version is exactly 11.0.1111 (matching the full four-part version number)
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Confirm VC6 file parsing capability is presentAttempt to access the File > Open dialog in Cobalt and look for .vc6 or VC6 file type support in the file type dropdown, or check program documentation/associated file types for .vc6 extension handling.Affected if VC6 file type support is available in the installation and the software can parse .vc6 files
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Review recent file open activity for VC6 filesCheck Windows Event Logs (Microsoft-Windows-ShellCore/Operational) or examine recent documents in the application's recent files list for any .vc6 files that were opened. Also review endpoint detection logs for Cobalt.exe file access events.Affected if VC6 files have been opened recently using the Cobalt application
A system is affected only if Ashlar Cobalt version 11.0.1111 is installed and the VC6 file parsing capability is present and has been used to open VC6 files.
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 dataAvoid opening untrusted VC6 files from unknown sources. Until a vendor patch is available, employ endpoint protection and consider network isolation for systems running this software.
- Consultation3.0 h
- Implementation6.0 h
- Testing5.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-34303 — 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-2023-34303 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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