CVE-2026-12296

Modified Modified - Updated After Analysis

Security Sandbox Escape in Firefox

Publication date: 2026-06-16

Last updated on: 2026-06-30

Assigner: Mozilla Corporation

Description

Sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, 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-2026-12296

EUVD

EUVD-2026-37087

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	firefox	to 152.0.0 (exc)
mozilla	thunderbird	to 152.0.0 (exc)
mozilla	firefox	to 140.12.0 (exc)
mozilla	thunderbird	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-403	A process does not close sensitive file descriptors before invoking a child process, which allows the child to perform unauthorized I/O operations using those descriptors.

Attack-Flow Graph

Executive Summary

This vulnerability is a sandbox escape in the Security: Process Sandboxing component of Mozilla Firefox. It allows an attacker to break out of the restricted sandbox environment that is designed to isolate processes, potentially gaining higher privileges or access to the system than intended.

The issue was addressed and fixed in Firefox version 152 and Firefox ESR 140.12.

Impact Analysis

By exploiting this sandbox escape vulnerability, an attacker could potentially execute code outside the sandbox restrictions, leading to unauthorized access to system resources or sensitive data.

This could result in compromise of the affected system's security, including possible data theft, system manipulation, or further exploitation.

Mitigation Strategies

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

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