VulnerabilityModified
CVE-2026-12294
This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.
CRITICAL 9.6EPSS 0.36%
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.36%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 9.6 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
- EPSS
- 0.36% probability · 30th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-693, CWE-266
- Affected
- mozilla/firefox · mozilla/thunderbird
- Source
- security@mozilla.org
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2039873Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-57/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-58/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-59/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-60/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-61/Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:27717
- https://access.redhat.com/errata/RHSA-2026:27733
- https://access.redhat.com/errata/RHSA-2026:27734
- https://access.redhat.com/errata/RHSA-2026:29940
- https://access.redhat.com/errata/RHSA-2026:30846
- https://access.redhat.com/errata/RHSA-2026:33445
- https://access.redhat.com/errata/RHSA-2026:36100
- https://access.redhat.com/errata/RHSA-2026:36101
- https://access.redhat.com/errata/RHSA-2026:36102
- https://access.redhat.com/errata/RHSA-2026:36103
- https://access.redhat.com/errata/RHSA-2026:37210
- https://access.redhat.com/errata/RHSA-2026:37391
- https://access.redhat.com/errata/RHSA-2026:38506
- https://access.redhat.com/errata/RHSA-2026:38750
- https://access.redhat.com/errata/RHSA-2026:38751
- https://access.redhat.com/errata/RHSA-2026:38753
- https://access.redhat.com/errata/RHSA-2026:39011
- https://access.redhat.com/errata/RHSA-2026:39141
- https://access.redhat.com/errata/RHSA-2026:39142
- https://access.redhat.com/errata/RHSA-2026:39428
- https://access.redhat.com/errata/RHSA-2026:39706
- https://access.redhat.com/security/cve/CVE-2026-12294
- https://bugzilla.redhat.com/show_bug.cgi?id=2489207
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-12294.json
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.