Meeting ServerApplication · Cisco
CVE-2021-40122
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 vulnerability in an API of the Call Bridge feature of Cisco Meeting Server could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. This vulnerability is due to improper handling of large series of message requests. An attacker could exploit this vulnerability by sending a series of messages to the vulnerable API. A successful exploit could allow the attacker to cause the affected device to reload, dropping all ongoing calls and resulting in a DoS condition.
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 confidenceA vulnerability in the Call Bridge API of Cisco Meeting Server allows unauthenticated remote attackers to cause denial of service by sending a large series of messages. The improper handling of these message requests causes the affected device to reload, dropping all ongoing calls.
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
Meeting ServerApplication
<= 3.1>= 3.2, < 3.2.3CVSS 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
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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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Confirm Cisco Meeting Server is deployedIdentify whether Cisco Meeting Server is installed in your environment by reviewing installed software, system inventory, or checking the product running on relevant servers.Affected if Cisco Meeting Server software is found in the environment
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Check installed version against affected rangesDetermine the installed version of Cisco Meeting Server using system administration interfaces, CLI show commands, or version information from the management interface. Compare this version to the affected ranges: versions <= 3.1 or >= 3.2 but < 3.2.3.Affected if Installed version is 3.1 or earlier, or is 3.2.x with x less than 3
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Verify Call Bridge API is network-accessibleDetermine if the Call Bridge API service port (typically port 443/TCP for HTTPS or as configured) is reachable from untrusted networks. Check firewall rules, ACLs, or network exposure settings for the Call Bridge API endpoint.Affected if Call Bridge API is accessible from unauthenticated or untrusted network segments without proper access controls
You are affected if Cisco Meeting Server is deployed with a version <= 3.1 or >= 3.2 but < 3.2.3, and the Call Bridge API is exposed to unauthenticated network access.
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.
dbcve · scoped3.2.3
Apply vendor-provided patches when available. In the interim, implement network-level rate limiting or access controls on the Call Bridge API to restrict excessive message requests from unauthenticated sources.
3.2.3 or later
- Identify the currently installed Cisco Meeting Server version
- Download Cisco Meeting Server version 3.2.3 or later from the Cisco software download page (requires valid Cisco service contract)
- Review the Cisco Meeting Server upgrade guide for your current version
- Plan a maintenance window as the upgrade will cause service interruption
- Back up the current configuration before proceeding
- Follow Cisco's official upgrade procedures to install version 3.2.3 or later
- Verify the upgrade was successful and all Call Bridge services are running properly
- Confirm that ongoing calls are not being dropped and the DoS condition is resolved
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Meeting Server
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-40122 — 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-2021-40122 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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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