Vulnerability Report

CVE-2026-2776

Title: Sandbox escape in Firefox and Thunderbird Telemetry component

Memory Corruption

Proof Of Concept

No public PoC currently indexed for CVE-2026-2776.

CWE Category NVD-CWE-noinfo

Published Date Feb 24, 2026

Modified Date Jul 15, 2026

Exploit Status Not Found

Score 10.0 CVSS v

Exploit Probability (EPSS)

0.48%

Vulnerability Summary

CVE-2026-2776: 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.

Impacted Vendors

mozilla 2

Reference Links

https://bugzilla.mozilla.org/show_bug.cgi?id=2015266 https://www.mozilla.org/security/advisories/mfsa2026-13/ https://www.mozilla.org/security/advisories/mfsa2026-14/ https://www.mozilla.org/security/advisories/mfsa2026-15/

CVSS v3.1

Source Entity [email protected]

Severity CRITICAL

10.0

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

CHANGED

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

CVSS v3.1

Source Entity 134c704f-9b21-4f2e-91b3-4a467353bcc0

Severity CRITICAL

10.0

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

CHANGED

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

CVSS v3.1

Source Entity 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

Severity HIGH

7.5

Attack Vector

NETWORK

Complexity

HIGH

Privileges

N/A

Interaction

REQUIRED

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

UNCHANGED

RAW VECTOR CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Associated Attack Patterns (CAPEC)

Total: Patterns