CVE-2026-2776

Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software

Critical · published February 24, 2026

CVSS v3.1
10.0
EPSS
1%
Percentile
52.8
In the wild
Unconfirmed
What it is

Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

The record
Technical detail
CVSS v3.1
10.0 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00704 · 52.8th percentile
Published
2026-02-24T13:33Z
EPSS history
Timeline
  • 24 FEB 13:33Z
    Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software
    cvelistv5