Incorrect handling of __proto__ mutations may lead to type confusion in IonMonkey JIT code and can be leveraged for arbitrary memory read and write. This vulnerability affects Firefox < 66.0.1, Firefox ESR < 60.6.1, and Thunderbird < 60.6.1.
https://access.redhat.com/errata/RHSA-2019:0966
https://access.redhat.com/errata/RHSA-2019:1144
https://bugzilla.mozilla.org/show_bug.cgi?id=1538006
https://www.mozilla.org/security/advisories/mfsa2019-09/
Source: MITRE
Published: 2019-04-26
Updated: 2020-08-24
Type: CWE-843
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