CVE-2026-2776

CRITICAL

Firefox <148 - Sandbox Escape

Title source: llm

Description

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

References (6)

[Issue Tracking] https://bugzilla.mozilla.org/show_bug.cgi?id=2015266

[Vendor Advisory] https://www.mozilla.org/security/advisories/mfsa2026-13/

[Vendor Advisory] https://www.mozilla.org/security/advisories/mfsa2026-14/

[Vendor Advisory] https://www.mozilla.org/security/advisories/mfsa2026-15/

[Vendor Advisory] https://www.mozilla.org/security/advisories/mfsa2026-16/

[Vendor Advisory] https://www.mozilla.org/security/advisories/mfsa2026-17/

Scores

CVSS v3 10.0

EPSS 0.0007

EPSS Percentile 21.5%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Classification

CWE

CWE-119

Status published

Affected Products (4)

mozilla/firefox < 115.33.0

mozilla/firefox < 148.0

mozilla/thunderbird < 140.8.0

mozilla/thunderbird < 148.0

Timeline

Published Feb 24, 2026

Tracked Since Feb 24, 2026