CVE-2019-9812

9.3 criticalEPSS 1.5%

Critical (9.3) in mozilla firefox. EPSS 1.5% chance of exploitation in the next 30 days.

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.

Severity

CVSS 3.1

9.3 critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:H

EPSS: 1.5% chance of exploitation in the next 30 days; higher than 74% of CVEs (scores of 2026-10-31)
Published: 2020-01-08
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

mozilla:firefox

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1538008
https://bugzilla.mozilla.org/show_bug.cgi?id=1538015
https://www.mozilla.org/security/advisories/mfsa2019-25/
https://www.mozilla.org/security/advisories/mfsa2019-26/
https://www.mozilla.org/security/advisories/mfsa2019-27/

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