CVE-2026-4701

Use-after-free in the JavaScript Engine component

Critical · published March 24, 2026

CVSS v3.1
9.8
EPSS
0%
Percentile
40.3
In the wild
Unconfirmed
What it is

Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00478 · 40.3th percentile
Published
2026-03-24T12:30Z
EPSS history
Timeline
  • 24 MAR 12:30Z
    Use-after-free in the JavaScript Engine component
    cvelistv5