CVE-2017-5420: Mozilla Firefox

Medium severity, CVSS 6.5. EPSS: 1.3% chance of exploitation in the next 30 days.

A "javascript:" url loaded by a malicious page can obfuscate its location by blanking the URL displayed in the addressbar, allowing for an attacker to spoof an existing page without the malicious page's address being displayed correctly. This vulnerability affects Firefox < 52.

Affected products

• Mozilla Firefox: before 52.0 (fixed in 52.0)

Published 2018-06-11. Last modified 2026-06-17.