CVE-2026-2763
CRITICALCVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3Description
Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.
Analysis
Use-after-free in Firefox JavaScript Engine before 148. One of multiple JS engine UAFs fixed in this release.
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Remediation
Within 24 hours: Inventory all Firefox and Thunderbird deployments across the organization and assess business-critical usage. Within 7 days: Implement browser isolation or network segmentation for affected systems; disable JavaScript execution where operationally feasible; communicate patch timeline to end-users and restrict non-essential browser usage. …
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