DOM Sandbox Escape Vulnerability in Firefox and Firefox ESR
CVE-2026-2778

10CRITICAL

Key Information:

Vendor

Mozilla
Status
Firefox
Firefox Esr
Thunderbird
Vendor
CVE Published:
24 February 2026

What is CVE-2026-2778?

A sandbox escape vulnerability has been identified in Firefox and Firefox ESR due to improper boundary conditions in the DOM components. This flaw could allow malicious content to break out of a restricted execution environment, potentially compromising user data and system integrity. Affected users are recommended to upgrade to the latest versions of Firefox and Firefox ESR to mitigate any risks associated with this vulnerability.

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Affected Version(s)

Firefox < 148

Firefox ESR < 115.33

Firefox ESR < 140.8

References

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/

CVSS V3.1

Score:
10
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Sajeeb Lohani
JSON
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