CVE-2018-5143

Name: CVE-2018-5143
Creator: NVD / NIST
Published: 2018-06-11T21:29:14.657+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

UnknownEPSS 0.94%

Last modified Jun 17, 2026

CVE-2018-5143 is a vulnerability of currently unknown severity. 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. EPSS estimates a 0.94% chance of exploitation in the next 30 days.

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.

Metrics

EPSS Probability

0.94%

56.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 59.0
Canonical	Ubuntu Linux	14.04
Canonical	Ubuntu Linux	16.04
Canonical	Ubuntu Linux	17.10

References

http://www.securityfocus.com/bid/103386Third Party Advisory, VDB Entry
http://www.securitytracker.com/id/1040514Third Party Advisory, VDB Entry
https://bugzilla.mozilla.org/show_bug.cgi?id=1422643Issue Tracking, Vendor Advisory
https://usn.ubuntu.com/3596-1/Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2018-06/Vendor Advisory
http://www.securityfocus.com/bid/103386Third Party Advisory, VDB Entry
http://www.securitytracker.com/id/1040514Third Party Advisory, VDB Entry
https://bugzilla.mozilla.org/show_bug.cgi?id=1422643Issue Tracking, Vendor Advisory
https://usn.ubuntu.com/3596-1/Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2018-06/Vendor Advisory

Timeline

Published: Jun 11, 2018
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-5143?

How severe is CVE-2018-5143?

Severity scoring for CVE-2018-5143 is pending analysis. The EPSS model estimates a 0.94% probability of exploitation in the next 30 days.

How do I fix CVE-2018-5143?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2018-5143?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST