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FirefoxWeb browser · Mozilla

CVE-2018-5113

HIGH · 7.5 CVSS v3.0 Published 2018-06-11
Fix available
A fix is available. Upgrade to after 57.0.4 or later.
See remediation →
84/100
Remediation priority · High
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
The "browser.identity.launchWebAuthFlow" function of WebExtensions is only allowed to load content over "https:" but this requirement was not properly enforced. This can potentially allow privileged pages to be loaded by the extension. This vulnerability affects Firefox < 58.

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

The browser.identity.launchWebAuthFlow WebExtension API, used for OAuth authentication flows, was designed to restrict URLs to HTTPS protocol only, but this requirement was improperly enforced. This allowed potentially unprivileged or malicious pages to be loaded within the extension's privileged context, bypassing the intended security boundary.

MitigationUpgrade Firefox to version 58 or later, which contains the proper HTTPS enforcement fix for the launchWebAuthFlow API.

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:<= 57.0.4
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 17.10

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
High
Integrity
None
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 installed Firefox version
    Run 'firefox --version' or go to Firefox > Help > About to see the version number
    Affected if Version is 57.0.4 or earlier (the fixed version is 58.0 or later)
  2. Identify WebExtensions using identity API
    Check installed extensions for use of 'browser.identity.launchWebAuthFlow' in their manifest.json or JavaScript files. Look in the ~/.mozilla/firefox/*/extensions/ directory or the browser's add-on manager.
    Affected if Any WebExtension is present that uses the launchWebAuthFlow API for OAuth flows
  3. Inspect OAuth redirect URI configuration
    For extensions using launchWebAuthFlow, examine their source code and OAuth configuration to identify the redirect_uri being used. This is typically found in the manifest.json permissions or the extension's JavaScript calling the API.
    Affected if The redirect_uri specified in the OAuth flow is HTTP (non-secure) rather than HTTPS, which the vulnerable code allowed
  4. Verify Ubuntu system Firefox package version
    On Ubuntu systems, run 'dpkg -l firefox' or 'apt-cache policy firefox' to check the installed Firefox package version
    Affected if Running Firefox 57.0.4 or earlier from Ubuntu packages on Ubuntu 14.04, 16.04, or 17.10

A user is affected if they are running Firefox version 57.0.4 or earlier AND have a WebExtension using the identity.launchWebAuthFlow API with an HTTP-based redirect URI, as the improper HTTPS enforcement allowed such non-secure flows to execute in a privileged context.

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 57.0.4
Interim mitigation

Upgrade Firefox to version 58 or later, which contains the proper HTTPS enforcement fix for the launchWebAuthFlow API.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation0.5 h
  • Testing1.0 h
  • Review / QA0.5 h
3.0 hours of engineering $750
Get the upgrade done

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

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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-2018-5113 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