Webex MeetingsApplication · Cisco
CVE-2021-40128
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 the account activation feature of Cisco Webex Meetings could allow an unauthenticated, remote attacker to send an account activation email with an activation link that points to an arbitrary domain. This vulnerability is due to insufficient validation of user-supplied parameters. An attacker could exploit this vulnerability by sending a crafted HTTP request to the account activation page of Cisco Webex Meetings. A successful exploit could allow the attacker to send to any recipient an account activation email that contains a tampered activation link, which could direct the user to an attacker-controlled website.
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 confidenceInsufficient validation of user-supplied parameters in Cisco Webex Meetings account activation feature allows an unauthenticated attacker to craft HTTP requests that inject arbitrary domains into activation links sent via email, directing users to attacker-controlled websites.
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
Webex MeetingsApplication
all versionsCVSS 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
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
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 Cisco Webex Meetings server is deployedReview your infrastructure to determine if you host or manage a Cisco Webex Meetings server installationAffected if You host or manage any Cisco Webex Meetings server instance - all versions are affected until patched by Cisco
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Check the installed Webex Meetings server versionAccess the Webex Meetings server administration interface or use the command-line interface to retrieve the installed version number. Consult Cisco documentation for your specific deployment type for version retrieval steps.Affected if The installed version has not been updated to include Cisco's patch for CVE-2021-40128 (contact Cisco for patched version numbers)
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Verify account activation feature exposureDetermine if the Webex Meetings account activation endpoint is accessible from untrusted networks. This typically involves checking firewall rules, network segmentation, or access controls around the Webex Meetings server.Affected if The account activation feature is exposed to unauthenticated attackers on untrusted networks
If you operate any Cisco Webex Meetings server instance that has not been patched by Cisco and has the account activation feature exposed to unauthenticated users, you are affected by this vulnerability.
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 dataApply Cisco's vendor patch for CVE-2021-40128; no customer-side mitigation available for this server-side parameter validation vulnerability.
Fix this in Webex Meetings
Scoped from the published advisory
- Consultation1.0 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 $1,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-40128 — 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-2021-40128 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