The Developer Tools feature suffers from a XUL injection vulnerability due to improper sanitization of the web page source code. In the worst case, this could allow arbitrary code execution when opening a malicious page with the style editor tool. This vulnerability affects Firefox ESR < 52.3 and Firefox < 55.
http://www.securityfocus.com/bid/100198
http://www.securitytracker.com/id/1039124
https://access.redhat.com/errata/RHSA-2017:2456
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1371586%2C1372112
https://www.debian.org/security/2017/dsa-3928
Source: MITRE
Published: 2018-06-11
Updated: 2018-08-09
Type: CWE-94
Base Score: 6.8
Vector: AV:N/AC:M/Au:N/C:P/I:P/A:P
Impact Score: 6.4
Exploitability Score: 8.6
Severity: MEDIUM
Base Score: 8.8
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Impact Score: 5.9
Exploitability Score: 2.8
Severity: HIGH