CVE-2017-7753: Mozilla: Out-of-bounds read with cached style data and pseudo-elements (MFSA 2017-19)

Severity: Critical

CVSS Score: 9.1

An out-of-bounds read occurs when applying style rules to pseudo-elements, such as ::first-line, using cached style data. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.