CVE-2021-3176
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 chat window of the Mitel BusinessCTI Enterprise (MBC-E) Client for Windows before 6.4.15 and 7.x before 7.1.2 could allow an attacker to gain access to user information by sending certain code, due to improper input validation of http links. A successful exploit could allow an attacker to view user information and application data.
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 confidenceThe Mitel BusinessCTI Enterprise (MBC-E) Client for Windows contains an input validation vulnerability in its chat window component. The application fails to properly validate HTTP links, allowing an attacker to inject malicious code through specially crafted links. This could enable unauthorized access to user information and application data.
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< 6.4.15>= 7.0, < 7.1.2CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/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.
-
Confirm MBC-E Client installationOpen Windows Control Panel or Settings > Apps & Features, and look for 'Mitel BusinessCTI Enterprise' or 'MBC-E Client' in the installed programs list.Affected if The application is not present on the system.
-
Identify installed versionRight-click the MBC-E Client shortcut or executable, select Properties, then view the Details tab for version information. Alternatively, open the application and check Help > About.Affected if Unable to locate version information.
-
Compare against affected versionsMatch the identified version number to the vulnerable ranges: versions below 6.4.15, or versions 7.0 through 7.1.1.Affected if Version is < 6.4.15 OR (version >= 7.0 AND version < 7.1.2).
-
Verify chat component usageDetermine if the user actively uses the chat/messaging feature within MBC-E Client, as this is the vulnerable component.Affected if Chat feature is enabled and actively used.
The environment is affected if MBC-E Client for Windows is installed with a version below 6.4.15 or between 7.0 and 7.1.1, and the chat window feature is in use.
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 data6.4.157.1.2
Apply vendor-supplied patches by updating MBC-E Client to version 6.4.15 or later (6.x) or 7.1.2 or later (7.x). Organizations should also consider network segmentation and user awareness training since this vulnerability is exploitable via chat messages.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-3176 — 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-2021-3176 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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
- No spam, self-promotion, credentials, or personal data