Memory safety bugs were reported in Firefox 49. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. This vulnerability affects Firefox < 50.
Severity
CVSS 3.0
9.8 critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
2.0% chance of exploitation in the next 30 days; higher than 80% of CVEs (scores of 2026-10-31)