dbcve.org
Zoom On Premise Meeting Connector ControllerApplication · Zoom

CVE-2021-34418

MEDIUM · 5.3 CVSS v3.1 Published 2021-11-11
Fix available
A fix is available. Upgrade to 2.5.5492.20200616 / 3.8.42.20200905 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 · unedited
The login routine of the web console in the Zoom On-Premise Meeting Connector before version 4.6.239.20200613, Zoom On-Premise Meeting Connector MMR before version 4.6.239.20200613, Zoom On-Premise Recording Connector before version 3.8.42.20200905, Zoom On-Premise Virtual Room Connector before version 4.4.6344.20200612, and Zoom On-Premise Virtual Room Connector Load Balancer before version 2.5.5492.20200616 fails to validate that a NULL byte was sent while authenticating. This could lead to a crash of the login service.

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 confidence

The login routine of the web console in multiple Zoom On-Premise components (Meeting Connector, Recording Connector, Virtual Room Connector, and Load Balancer) fails to validate NULL byte input during authentication. This improper input validation can cause the login service to crash, resulting in denial of service.

MitigationUpgrade to the patched versions: Meeting Connector/MMR before 4.6.239.20200613, Recording Connector before 3.8.42.20200905, Virtual Room Connector before 4.4.6344.20200612, and Load Balancer before 2.5.5492.20200616.

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
Zoom On Premise Meeting Connector ControllerApplication
Affected:< 4.6.239.20200613
Zoom On Premise Meeting Connector MmrApplication
Affected:< 4.6.239.20200613
Zoom On Premise Recording ConnectorApplication
Affected:< 3.8.42.20200905
Zoom On Premise Virtual Room ConnectorApplication
Affected:< 4.4.6344.20200612
Zoom On Premise Virtual Room Connector Load BalancerApplication
Affected:< 2.5.5492.20200616

CVSS 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
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Zoom On-Premise components
    Review your environment for any of the following Zoom On-Premise components: Meeting Connector Controller, Meeting Connector MMR, Recording Connector, Virtual Room Connector, or Virtual Room Connector Load Balancer. Check running services, installed packages, or documentation of deployed infrastructure.
    Affected if Any of these five components are present in the environment.
  2. Determine the version of Meeting Connector components
    Locate the version information for the Meeting Connector Controller and/or Meeting Connector MMR installations. Consult the product documentation for your deployment type to find where version metadata is stored (such as in configuration files, about pages, or management interfaces).
    Affected if The installed version is earlier than 4.6.239.20200613.
  3. Determine the version of Recording Connector
    Locate the version information for the Recording Connector installation. Check product documentation for your deployment method to find version details.
    Affected if The installed version is earlier than 3.8.42.20200905.
  4. Determine the version of Virtual Room Connector
    Locate the version information for the Virtual Room Connector installation. Consult deployment-specific documentation to find where version metadata is exposed.
    Affected if The installed version is earlier than 4.4.6344.20200612.
  5. Determine the version of Virtual Room Connector Load Balancer
    Locate the version information for the Load Balancer component installation. Check product documentation for version retrieval methods.
    Affected if The installed version is earlier than 2.5.5492.20200616.
  6. Confirm web console is accessible
    Verify that the web console login service for the Zoom On-Premise component is running and reachable on the network. The vulnerability affects the login routine, so the web service must be active for the denial of service to occur.
    Affected if The web console login service is exposed and operational.

You are affected if any Zoom On-Premise component (Meeting Connector, Recording Connector, Virtual Room Connector, or Load Balancer) is deployed with a version earlier than the threshold listed for that product, and the web console login service is running.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to 2.5.5492.20200616 / 3.8.42.20200905 / 4.4.6344.20200612 or later
Fixed in 2.5.5492.202006163.8.42.202009054.4.6344.20200612
Interim mitigation

Upgrade to the patched versions: Meeting Connector/MMR before 4.6.239.20200613, Recording Connector before 3.8.42.20200905, Virtual Room Connector before 4.4.6344.20200612, and Load Balancer before 2.5.5492.20200616.

Recommended fix High confidence

Meeting Connector Controller/MMR: 4.6.239.20200613 | Recording Connector: 3.8.42.20200905 | Virtual Room Connector: 4.4.6344.20200612 | Virtual Room Connector Load Balancer: 2.5.5492.20200616

  1. 1. Identify which Zoom On-Premise product(s) are deployed in your environment (Meeting Connector Controller, Meeting Connector MMR, Recording Connector, Virtual Room Connector, or Virtual Room Connector Load Balancer)
  2. 2. Check the current version of each installed product
  3. 3. For Zoom On Premise Meeting Connector Controller: upgrade to version 4.6.239.20200613 or later
  4. 4. For Zoom On Premise Meeting Connector MMR: upgrade to version 4.6.239.20200613 or later
  5. 5. For Zoom On Premise Recording Connector: upgrade to version 3.8.42.20200905 or later
  6. 6. For Zoom On Premise Virtual Room Connector: upgrade to version 4.4.6344.20200612 or later
  7. 7. For Zoom On Premise Virtual Room Connector Load Balancer: upgrade to version 2.5.5492.20200616 or later
  8. 8. After upgrading, restart the login service and verify that authentication functions properly without crashes

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Zoom On Premise Meeting Connector Controller Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-34418 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-34418 in production — separate from our analysis above.

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.

What this is

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.

What belongs here
  • 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