CVE-2026-12294

Sandbox escape in the DOM: Workers component

Published Jun 16, 2026 CVSS 3.1 · 9.6 Critical EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4635-1 firefox-esr security update
Debian DLA Debian DLA DLA-4636-1 thunderbird security update
Debian DSA Debian DSA DSA-6350-1 firefox-esr security update
Debian DSA Debian DSA DSA-6351-1 thunderbird security update
References
Link Providers
https://access.redhat.com/errata/RHSA-2026:27717 cve-icon
https://access.redhat.com/errata/RHSA-2026:27733 cve-icon
https://access.redhat.com/errata/RHSA-2026:27734 cve-icon
https://access.redhat.com/errata/RHSA-2026:29940 cve-icon
https://access.redhat.com/errata/RHSA-2026:30846 cve-icon
https://access.redhat.com/errata/RHSA-2026:33445 cve-icon
https://access.redhat.com/errata/RHSA-2026:36100 cve-icon
https://access.redhat.com/errata/RHSA-2026:36101 cve-icon
https://access.redhat.com/errata/RHSA-2026:36102 cve-icon
https://access.redhat.com/errata/RHSA-2026:36103 cve-icon
https://access.redhat.com/errata/RHSA-2026:37210 cve-icon
https://access.redhat.com/errata/RHSA-2026:37391 cve-icon
https://access.redhat.com/errata/RHSA-2026:38506 cve-icon
https://access.redhat.com/errata/RHSA-2026:38750 cve-icon
https://access.redhat.com/errata/RHSA-2026:38751 cve-icon
https://access.redhat.com/errata/RHSA-2026:38753 cve-icon
https://access.redhat.com/errata/RHSA-2026:39011 cve-icon
https://access.redhat.com/errata/RHSA-2026:39141 cve-icon
https://access.redhat.com/errata/RHSA-2026:39142 cve-icon
https://access.redhat.com/errata/RHSA-2026:39428 cve-icon
https://access.redhat.com/errata/RHSA-2026:39706 cve-icon
https://access.redhat.com/security/cve/CVE-2026-12294 cve-icon
https://bugzilla.mozilla.org/show_bug.cgi?id=2039873 cve-icon cve-icon
https://bugzilla.redhat.com/show_bug.cgi?id=2489207 cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-12294 cve-icon
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-12294.json cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-12294 cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-57/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-58/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-58/#CVE-2026-12294 cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-59/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-60/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-61/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-61/#CVE-2026-12294 cve-icon
History
Type Values Removed Values Added
Weaknesses CWE-284
CWE-285
Type Values Removed Values Added
Weaknesses CWE-693
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

cvssV3_1

{'score': 9.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H'}

Type Values Removed Values Added
Weaknesses CWE-284
CWE-285
Type Values Removed Values Added
Description Sandbox escape in the DOM: Workers component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, and Firefox ESR 115.37. 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.
References
Type Values Removed Values Added
First Time appeared Mozilla
Mozilla firefox
Vendors & Products Mozilla
Mozilla firefox
Type Values Removed Values Added
Description Sandbox escape in the DOM: Workers component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, and Firefox ESR 115.37.
Title Sandbox escape in the DOM: Workers component
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
mozilla
Published
Updated
Jul 15, 2026, 11:48 AM
Reserved
Jun 15, 2026, 3:08 PM
Status
Modified
Published
Jun 16, 2026, 1:16 PM
Modified
Oct 26, 2026, 1:10 PM
Severity
Important
Public date
Jun 16, 2026, 11:52 AM