CVE-2019-9812
CVE-2019-9812 is a critical-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 9.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.
Key facts
- Severity: Critical (CVSS 3.x base score 9.3)
- CVSS v2: 5.8
- EPSS exploit prediction: 1% (67th percentile)
- Actively exploited: Not listed in CISA KEV
- Affected product: Mozilla Firefox
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2019-9812?
- 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.
- How severe is CVE-2019-9812?
- CVE-2019-9812 has a CVSS 3.x base score of 9.3, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability high.
- Is CVE-2019-9812 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2019-9812?
- CVE-2019-9812 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2019-9812?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2019-9812 published?
- CVE-2019-9812 was published on 2020-01-08 and last updated on 2026-06-17.
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/
Affected products (1)
- cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
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