Given a compromised sandboxed content process due to a separate vulnerability, it is possible to escape that sandbox by loading accounts.firefox.com in that process and forcing a log-in to a malicious Firefox Sync account. Preference settings that disable the sandbox are then synchronized to the local machine and the compromised browser would restart without the sandbox if a crash is triggered. This vulnerability affects Firefox ESR < 60.9, Firefox ESR < 68.1, and Firefox < 69. Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-9812 Reference (s):
- https://bugzilla.mozilla.org/show_bug.cgi?id=1538008
- https://www.mozilla.org/security/advisories/mfsa2019-25/
- https://www.mozilla.org/security/advisories/mfsa2019-26/
- https://www.mozilla.org/security/advisories/mfsa2019-27/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1538015