CVE-2018-5143

Severity: medium (CVSS 6.1 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2018-06-11 · updated 2026-06-17
Weakness: CWE-79

Description

URLs using "javascript:" have the protocol removed when pasted into the addressbar to protect users from cross-site scripting (XSS) attacks, but if a tab character is embedded in the "javascript:" URL the protocol is not removed and the script will execute. This could allow users to be socially engineered to run an XSS attack against themselves. This vulnerability affects Firefox < 59.

Affected products

Canonical Ubuntu Linux: 14.04, 16.04, 17.10
Mozilla Firefox: before 59.0 — fixed in 59.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 59.0. Check the vendor advisory for mitigations.

References

http://www.securityfocus.com/bid/103386
http://www.securitytracker.com/id/1040514
https://bugzilla.mozilla.org/show_bug.cgi?id=1422643
https://usn.ubuntu.com/3596-1/
https://www.mozilla.org/security/advisories/mfsa2018-06/
http://www.securityfocus.com/bid/103386
http://www.securitytracker.com/id/1040514
https://bugzilla.mozilla.org/show_bug.cgi?id=1422643
https://usn.ubuntu.com/3596-1/
https://www.mozilla.org/security/advisories/mfsa2018-06/

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