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VulnerabilityCVE-2026-12294Published 2026-06-16

CVE-2026-12294 — Mozilla Firefox

critical

As of 2026-07-15, CVE-2026-12294 is a CRITICAL-severity vulnerability in Mozilla Firefox, CVSS v3.1 9.6, EPSS 0.3% (28.0th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-12294, most recently “Multiple Vulnerabilities in Firefox 152 Enable Remote Code Execution and Sandbox Escape (MFSA 2026-57)”.

CVSS v3.1
9.6/10Critical
EPSS
0.3%Higher than 28.0% of scored CVEs
CISA KEV
NoNot in the KEV catalog
Tracked threats
1Campaigns referencing it
Priority
5.9/10Threadlinqs triage score
Published
Updated 2026-07-15
CVSS v3.1 9.6 (CRITICAL) · EPSS 0.3% (higher than 28.0% of all scored CVEs) · Priority 5.9/10 · Published 2026-06-16

Last updated:

What is CVE-2026-12294?

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.

The record classifies CVE-2026-12294 under weakness classes CWE-693, CWE-266. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 2 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 116 days ago.

Severity and exploitation probability

CVSS v3.1 base score
9.6 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
EPSS (FIRST)
0.3% probability of exploitation in the next 30 days, higher than 28.0% of all scored CVEs
CISA KEV
Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority
5.9/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
Published
2026-06-16, last modified 2026-07-15

Is CVE-2026-12294 being exploited?

It currently carries a trending score of 13 in the Threadlinqs vulnerability feed.

Affected products and versions

How to fix CVE-2026-12294

Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-57/. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2026-12294

1 tracked threat in the Threadlinqs corpus references CVE-2026-12294, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.

Other references

Showing 5 of 6 recorded references.