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Webex TeamsApplication · Cisco

CVE-2023-20104

MEDIUM · 6.1 CVSS v3.1 Published 2023-03-03
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges

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
A vulnerability in the file upload functionality of Cisco Webex App for Web could allow an unauthenticated, remote attacker to conduct a cross-site scripting (XSS) attack against a user of the interface. This vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending an arbitrary file to a user and persuading that user to browse to a specific URL. A successful exploit could allow the attacker to execute arbitrary script code in the context of the affected interface or access sensitive, browser-based information.

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

Cross-site scripting (XSS) vulnerability in Cisco Webex App for Web's file upload functionality. An unauthenticated remote attacker can send a malicious file to a user and persuade them to visit a specific URL, allowing arbitrary script execution in the context of the affected interface due to insufficient validation of user-supplied input.

MitigationApply Cisco's official patch for CVE-2023-20104 when available. Users should avoid opening files from untrusted sources and refrain from visiting suspicious URLs until the vulnerability is remediated.

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 TeamsApplication
Affected:all versions

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
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/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 checks

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

  1. Confirm Webex App for Web usage
    Identify if users are accessing Cisco Webex through a web browser (webex.com) rather than the desktop/mobile application. Check browser history or ask users which platform they primarily use.
    Affected if Users access Webex through a web browser at webex.com, as the vulnerability exists in the web version only.
  2. Inspect recent file uploads
    Review any recently uploaded files through Webex for unexpected script tags, HTML content, or base64-encoded payloads that may contain malicious JavaScript.
    Affected if Files containing unsanitized script tags, event handlers, or suspicious JavaScript code were uploaded via the Webex web interface.
  3. Check browser console for XSS errors
    Ask users to open browser developer tools (F12), go to the Console tab, and look for error messages related to blocked scripts, Content Security Policy violations, or unexpected script execution.
    Affected if Console shows XSS-related security errors or unexpected script execution attempts originating from Webex.
  4. Review browser network activity
    In browser developer tools, examine the Network tab for any requests to external domains or suspicious URL patterns that may indicate script exfiltration or redirect attempts after file upload.
    Affected if Network requests show unexpected redirects, external script loading, or communication with suspicious domains following Webex file interactions.
  5. Look for signs of unauthorized script execution
    Ask users to check if they experienced unexpected pop-ups, page redirects, or if their session behaved strangely after opening a file shared via Webex web.
    Affected if Users report unexpected browser behavior, unauthorized actions performed under their session, or anomalous pop-ups after opening shared files.

A user is affected if they access Cisco Webex through a web browser and have opened or interacted with a maliciously crafted file uploaded through the web interface, or if they notice XSS indicators in their browser console or unexpected script execution.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Cisco's official patch for CVE-2023-20104 when available. Users should avoid opening files from untrusted sources and refrain from visiting suspicious URLs until the vulnerability is remediated.

Fix this in Webex Teams Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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 sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-20104 in production — separate from our analysis above.

No notes yet

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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