CVE-2020-12456
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 · uneditedA remote code execution vulnerability in Mitel MiVoice Connect Client before 214.100.1223.0 could allow an attacker to execute arbitrary code in the chat notification window, due to improper rendering of chat messages. A successful exploit could allow an attacker to steal session cookies, perform directory traversal, and execute arbitrary scripts in the context of the Connect client.
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 confidenceMitel MiVoice Connect Client before version 214.100.1223.0 contains a remote code execution vulnerability in the chat notification window caused by improper rendering of chat messages. Attackers can inject malicious scripts through chat messages that execute in the context of the Connect client, enabling session cookie theft, directory traversal, and arbitrary script execution.
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< 214.100.1223.0CVSS 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
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/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 if Mitel MiVoice Connect Client is installedCheck the installed programs list in Windows Control Panel > Programs and Features, or look for the application in the installation directory (typically C:\Program Files\Mitel\MiVoice Connect Client or C:\Program Files (x86)\Mitel\MiVoice Connect Client)Affected if The application is present on the system and the chat feature is used
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Determine the installed version of MiVoice Connect ClientRight-click the client executable (typically named MitelConnect.exe or similar), select Properties, and view the Version tab. Alternatively, open the client and check Help > About, or examine the version in the Windows Registry under HKLM\SOFTWARE\Mitel\MiVoice Connect or HKCU\SOFTWARE\Mitel\MiVoice ConnectAffected if The installed version number is lower than 214.100.1223.0 (for example, 214.100.1000.0, 214.x.x.x versions below 214.100.1223.0, or any 19x.x.x.x version)
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Confirm chat notification feature is enabledWithin the client, navigate to Settings > Notifications or Settings > Chat to verify that chat message notifications are enabled. This feature is often enabled by default for collaborative functionalityAffected if Chat notifications are enabled and the client receives external chat messages from other users or servers
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Review chat message logs for suspicious contentCheck the client's log files (typically located in %APPDATA%\Mitel\MiVoice Connect\Logs or the installation folder) for any chat messages containing unusual script tags, HTML entities, or path-like strings that could indicate exploitation attemptsAffected if Log files contain chat messages with encoded scripts, directory traversal patterns (../), or unexpected HTML/script content
You are affected if Mitel MiVoice Connect Client is installed with a version lower than 214.100.1223.0 and chat notification functionality is enabled, as the vulnerability requires the client to process incoming chat messages to execute injected scripts.
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 data214.100.1223.0
Upgrade Mitel MiVoice Connect Client to version 214.100.1223.0 or later to remediate the improper message rendering vulnerability. Until patched, restrict or disable chat functionality and monitor for suspicious chat messages.
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- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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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-2020-12456 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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