Vulnerability Report

CVE-2026-2778

Title: Sandbox escape due to incorrect boundary conditions in Firefox and Thunderbird DOM: Core & HTML

Memory Corruption

Proof Of Concept

No public PoC currently indexed for CVE-2026-2778.

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-2026-2778: Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. 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=2016358 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