A "javascript:" url loaded by a malicious page can obfuscate its location by blanking the URL displayed in the addressbar, allowing for an…

published 2018-06-11 8 y ago modified 2026-06-17 4 mo ago also EUVD-2017-14524

cvss: 6.5; version 3.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.3%; EPSS 1.3% chance of exploitation in 30 days, percentile 69%
public exploits: 0; none known

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.

Patch / fix

fixed in 1 distros 3 links 1

Mozilla Firefox 52

ubuntu opensuse arch linux

firefox Ubuntu 14.04 LTS 52.0+build2-0ubuntu0.14.04.1
firefox Ubuntu 16.04 LTS 52.0+build2-0ubuntu0.16.04.1

ubuntu advisories UBUNTU-CVE-2017-5420

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

firefox-esr openSUSE Tumbleweed 128.5.1-1.1
MozillaFirefox openSUSE Tumbleweed 92.0-1.2

opensuse advisories openSUSE-SU-2024:14572-1 openSUSE-SU-2024:10600-1

firefox Arch Linux 52.0-1

arch linux advisories AVG-194

bugzilla.mozilla.org/show_bug.cgi?id=1284395 advisory

Exploit prediction

1.25% chance of exploitation in the next 30 days, higher than 69% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=1284395 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.0	6.5	CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
NVD	2.0	4.3	AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

Mozilla Firefox

Classification

Weakness

CWE-20 Improper Input Validation

References

bugzilla.mozilla.org /show_bug.cgi?id=1284395
exploit, issue-tracking, patch, vendor-advisory
mozilla.org /security/advisories/mfsa2017-05/
vendor-advisory
securitytracker.com /id/1037966
vdb-entry, third-party-advisory
securityfocus.com /bid/96692
vdb-entry, third-party-advisory

Sources

CVE List CVE-2017-5420
NVD CVE-2017-5420

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary