The Script.prototype.freeze/thaw functionality in Mozilla 1.4 and earlier allows attackers to execute native methods by modifying the string used as input to the script.thaw JavaScript function, which is then deserialized and executed.
Severity
CVSS 3.1
9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
2.1% chance of exploitation in the next 30 days; higher than 81% of CVEs (scores of 2026-10-31)