CVE-2026-12294

Modified Modified - Updated After Analysis

DOM Worker Sandbox Escape in Firefox

Publication date: 2026-06-16

Last updated on: 2026-06-30

Assigner: Mozilla Corporation

Description

Sandbox escape in the DOM: Workers component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-06-16

Last Modified

2026-06-30

Generated

2026-07-06

AI Q&A

2026-06-16

EPSS Evaluated

2026-07-05

NVD

CVE-2026-12294

EUVD

EUVD-2026-37085

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	firefox	to 152.0.0 (exc)
mozilla	firefox	to 115.37.0 (exc)
mozilla	thunderbird	to 152.0.0 (exc)
mozilla	thunderbird	to 140.12.0 (exc)
mozilla	firefox	From 128.0 (inc) to 140.12.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-693	The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.
CWE-266	A product incorrectly assigns a privilege to a particular actor, creating an unintended sphere of control for that actor.

Attack-Flow Graph

Executive Summary

This vulnerability is a sandbox escape in the DOM: Workers component of Mozilla Firefox. It allows code running in a restricted environment (sandbox) to break out of those restrictions, potentially gaining higher privileges or access than intended. The issue was fixed in Firefox versions 152, Firefox ESR 140.12, and Firefox ESR 115.37.

Impact Analysis

This vulnerability could allow malicious code running within a sandboxed environment in Firefox to escape those restrictions, potentially leading to unauthorized access to system resources or sensitive data. This could compromise the security and privacy of the user by allowing attackers to execute code with elevated privileges.

Mitigation Strategies

To mitigate this vulnerability, update Firefox to version 152 or later, or update Firefox ESR to version 140.12 or later, or ESR 115.37 or later where the issue has been fixed.

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