The JSON viewer in the Developer Tools uses insecure methods to create a communication channel for copying and viewing JSON or HTTP headers data, allowing for potential privilege escalation. This vulnerability affects Thunderbird < 45.7, Firefox ESR < 45.7, and Firefox < 51.
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
3.8% chance of exploitation in the next 30 days; higher than 90% of CVEs (scores of 2026-10-31)