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FirefoxWeb browser · Mozilla

CVE-2019-9808

MEDIUM · 5.3 CVSS v3.0 Published 2019-04-26
Fix available
A fix is available. Upgrade to 66.0 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
If WebRTC permission is requested from documents with data: or blob: URLs, the permission notifications do not properly display the originating domain. The notification states "Unknown origin" as the requestee, leading to user confusion about which site is asking for this permission. This vulnerability affects Firefox < 66.

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

WebRTC permission prompts fail to display the correct originating domain when requests originate from data: or blob: URLs, showing 'Unknown origin' instead. This occurs because these URL types lack a proper origin context that the permission notification system can resolve, leading to misleading permission prompts.

MitigationUpgrade Firefox to version 66 or later, which contains the fix for properly resolving origins from data: and blob: URLs in WebRTC permission dialogs.

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
FirefoxWeb browser
Affected:< 66.0

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
Low
Availability
None

CVSS:3.0/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 checks

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

  1. Check Firefox version
    Navigate to Menu > Help > About Firefox, or enter 'about:support' in the address bar, or run 'firefox --version' from command line
    Affected if Firefox version is below 66.0 (e.g., 65.x, 64.x, etc.)
  2. Verify WebRTC is accessible
    Ensure WebRTC functionality is available in the Firefox instance - this is a built-in feature, no special configuration needed
    Affected if WebRTC APIs are functional in the browser environment being tested
  3. Test permission prompt behavior (optional confirmation)
    Use a WebRTC application or test page that triggers a camera/microphone permission prompt. Observe whether the origin displayed is 'Unknown origin' or shows an actual domain
    Affected if Permission prompt displays 'Unknown origin' instead of the expected domain for data: or blob: URL-based requests

A user is affected if they are running Mozilla Firefox version 66.0 or newer and observe 'Unknown origin' in WebRTC permission prompts when requests originate from data: or blob: URLs, though versions below 66.0 are the primary affected range.

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
Upgrade available Upgrade to 66.0 or later
Fixed in 66.0
Interim mitigation

Upgrade Firefox to version 66 or later, which contains the fix for properly resolving origins from data: and blob: URLs in WebRTC permission dialogs.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
3.0 hours of engineering $750
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,200.

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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-2019-9808 in production — separate from our analysis above.

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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
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