CVE-2014-8240
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 · uneditedInteger overflow in TigerVNC allows remote VNC servers to cause a denial of service (crash) and possibly execute arbitrary code via vectors related to screen size handling, which triggers a heap-based buffer overflow, a similar issue to CVE-2014-6051.
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 confidenceInteger overflow in TigerVNC's screen size handling allows a malicious VNC server to trigger a heap-based buffer overflow, potentially causing client crash (DoS) or arbitrary code execution. This is a client-side vulnerability where the VNC viewer fails to properly validate screen dimension values received from the server.
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= 0.0.90= 0.0.91= 1.0.0= 1.0.1= 1.1.0CVSS 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
- Network
- Complexity
- Low
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:L/Au:N/C:P/I:P/A:P
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 if TigerVNC client is installedLook for TigerVNC binaries such as vncviewer, vncconfig, or the TigerVNC application in common installation locations (e.g., /usr/bin/vncviewer, C:\Program Files\TigerVNC\vncviewer.exe, or check system package manager)Affected if TigerVNC client software is present on the system
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Determine the installed TigerVNC versionRun 'vncviewer -version' or check the program's version information through your OS package manager (dpkg -l tigervnc, rpm -qi tigervnc, or similar)Affected if The installed version matches one of the affected versions: 0.0.90, 0.0.91, 1.0.0, 1.0.1, or 1.1.0
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Verify if the client connects to external or untrusted VNC serversReview VNC connection configurations, saved connections, or scripts that invoke vncviewer to identify target serversAffected if The TigerVNC client is configured to connect to servers outside your trusted network, as the vulnerability is triggered by a malicious server sending oversized screen dimensions
You are affected if you have TigerVNC client version 0.0.90, 0.0.91, 1.0.0, 1.0.1, or 1.1.0 installed and use it to connect to VNC servers, particularly untrusted or external ones.
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 TigerVNC to the latest patched version that addresses this integer overflow vulnerability. If immediate patching is not possible, restrict VNC connections to trusted servers only.
- 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-2014-8240 — 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-2014-8240 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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