CVE-2018-5138

Original summary

Normalized public record · Updated Nov 3, 2026

A spoofing vulnerability can occur when a malicious site with an extremely long domain name is opened in an Android Custom Tab (a browser panel inside another app) and the default browser is Firefox for Android. This could allow an attacker to spoof which page is actually loaded and in use. Note: this issue only affects Firefox for Android. Other versions and operating systems are unaffected. This vulnerability affects Firefox < 59.

Publisher and source text is retained separately from QFinch interpretation.

Affected products

Matching a version is only one part of assessing exposure. QFinch has not assessed your environment on this public page.

Remediation

Apply the vendor-supported fixed release or mitigation, then verify the affected component is no longer reachable.

1. Confirm the affected product and reachable code path exist in your environment.
2. Apply the vendor-supported patch or mitigation from the primary advisory.
3. Rescan the exact deployed revision and retain verification evidence.

Evidence coverage

SSVC priority

LOW

Confidence

Not available

Aliases

None reported

Scores appear only when corresponding evidence exists. Missing data is never interpreted as zero risk.

Sources and record history

1. 103386 ↗
2. bugzilla.mozilla.org ↗
3. 1040514 ↗
4. Security advisory ↗

Record history

Published Jun 11, 2018 · Last refreshed Nov 3, 2026