CVE-2019-9812

Name: CVE-2019-9812
Creator: NVD / NIST
Published: 2020-01-08T22:15:13.31+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.3/10EPSS 1.30%

Last modified Jun 17, 2026

CVE-2019-9812 is a critical-severity vulnerability rated 9.3/10 on the CVSS scale. 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. EPSS estimates a 1.30% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

9.3/10

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

EPSS Probability

1.30%

66.8th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 60.9
Mozilla	Firefox	< 69.0
Mozilla	Firefox	>= 61.0, < 68.1

References

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

Timeline

Published: Jan 8, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2019-9812?

How severe is CVE-2019-9812?

CVE-2019-9812 has a CVSS score of 9.3/10 (CRITICAL severity). The EPSS model estimates a 1.30% probability of exploitation in the next 30 days.

How do I fix CVE-2019-9812?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2019-9812?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST