CVE-2026-12294: Sandbox escape in the DOM: Workers component

Published Jun 16, 2026
·
Updated

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.

Affected Software

10 affected componentsFixes available
Mozilla Firefox ESR<140.12
140.12
Mozilla Firefox<152
152
Mozilla Firefox ESR<115.37
115.37
Mozilla Thunderbird<140.12
140.12
Mozilla Thunderbird<152
152
Mozilla Firefox<115.37.0
Mozilla Firefox<152.0.0
Mozilla Firefox>=128.0<140.12.0
Mozilla Thunderbird<140.12.0
Mozilla Thunderbird<152.0.0

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 140.12
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 152
  3. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 115.37
  4. Upgrade

    Upgrade Firefox to a version that resolves this vulnerability.

    Fixed in 152
  5. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 140.12
  6. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 115.37
  7. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 152
  8. Upgrade

    Upgrade Thunderbird ESR to a version that resolves this vulnerability.

    Fixed in 140.12

Event History

Jun 16, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Updated
via Mozilla·12:00 AM
Affected Software
CVE Published
via MITRE·11:52 AM
Data Sourced
via MITRE·11:52 AM
Description
Data Sourced
via NVD·01:16 PM
DescriptionSeverityWeaknessAffected Software
Data Sourced
via Red Hat·02:01 PM
DescriptionSeverityAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

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Frequently Asked Questions

1

What is the severity of CVE-2026-12294?

CVE-2026-12294 is rated critical with a CVSS score of 9.6.

2

How do I fix CVE-2026-12294?

To fix CVE-2026-12294, update to Firefox 152, Firefox ESR 140.12, or Thunderbird 152.

3

What products are affected by CVE-2026-12294?

CVE-2026-12294 affects Mozilla Firefox, Mozilla Thunderbird, and Firefox ESR.

4

What is the risk associated with CVE-2026-12294?

CVE-2026-12294 has a risk score of 80, indicating a significant threat.

5

What type of vulnerability is CVE-2026-12294?

CVE-2026-12294 is a sandbox escape vulnerability found in the DOM: Workers component.

Company

Resources

Contact

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