What is CVE-2026-12302?
Mitigation bypass in the DOM: Security 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-2026-12302 under weakness class CWE-693. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction. 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
- 6.5 — MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N - EPSS (FIRST)
- 0.2% probability of exploitation in the next 30 days, higher than 14.7% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 3.8/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-06-16
Is CVE-2026-12302 being exploited?
It currently carries a trending score of 10 in the Threadlinqs vulnerability feed.
Affected products and versions
- Mozilla: Firefox, Thunderbird
How to fix CVE-2026-12302
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-2026-12302
1 tracked threat in the Threadlinqs corpus references CVE-2026-12302, 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
- bugzilla.mozilla.org
- mozilla.org
- mozilla.org (mfsa2026 58)
- mozilla.org (mfsa2026 59)
- mozilla.org (mfsa2026 60)
Showing 5 of 6 recorded references.