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FirefoxWeb browser · Mozilla

CVE-2015-7197

MEDIUM · 5.0 CVSS v2.0 Published 2015-11-05
Fix available
A fix is available. Upgrade to after 41.0.2 or later.
See remediation →
59/100
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
Mozilla Firefox before 42.0 and Firefox ESR 38.x before 38.4 improperly control the ability of a web worker to create a WebSocket object, which allows remote attackers to bypass intended mixed-content restrictions via crafted JavaScript code.

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

Firefox before 42.0 and ESR 38.x before 38.4 had improper access controls on WebSocket creation within web workers, allowing them to establish WebSocket connections regardless of mixed-content restrictions. This enabled attackers to bypass same-origin policy protections by using web workers on HTTPS pages to connect to HTTP endpoints via WebSocket.

MitigationUpgrade Firefox to version 42.0 or later, or Firefox ESR to 38.4 or later, to enforce proper mixed-content restrictions on WebSocket connections from web workers.

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:<= 41.0.2= 38.0= 38.0.1= 38.0.5= 38.1.0= 38.1.1= 38.2.0= 38.2.1= 38.3.0

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
Authentication
None
Confidentiality
None
Integrity
Partial
Availability
None

AV:N/AC:L/Au:N/C:N/I:P/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
    Open Firefox, click the menu button, go to Help > About Firefox. The version number will be displayed.
    Affected if Version is 41.0.2 or lower, or is one of: 38.0, 38.0.1, 38.0.5, 38.1.0, 38.1.1, 38.2.0, 38.2.1, or 38.3.0 (ESR versions)
  2. Identify if using ESR release
    In About Firefox window, look for 'ESR' in the version string. For example: '38.3.0 (ESR)' indicates an Extended Support Release.
    Affected if Running an ESR version listed in the affected versions (38.x before 38.4)
  3. Confirm WebSocket usage in web workers
    Inspect web application code for WebSocket creation inside Web Worker scripts (new WebSocket() inside a worker file or blob). Check if the parent page loads over HTTPS while the WebSocket connects to an HTTP endpoint.
    Affected if Web workers on HTTPS pages are establishing WebSocket connections to HTTP (non-secure) endpoints, bypassing mixed-content restrictions

You are affected if you run Firefox 41.0.2 or earlier, or Firefox ESR 38.3.0 or earlier, and use web workers that create WebSocket connections to HTTP endpoints from HTTPS pages.

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 a release after 41.0.2
Interim mitigation

Upgrade Firefox to version 42.0 or later, or Firefox ESR to 38.4 or later, to enforce proper mixed-content restrictions on WebSocket connections from web workers.

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.

Scan for this in your stack

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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-2015-7197 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