CVE-2026-12298 — Mozilla Firefox Vulnerability

What is CVE-2026-12298?

Memory safety bug fixed in Firefox 152. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.

The record classifies CVE-2026-12298 under weakness classes CWE-125, CWE-787, CWE-416, CWE-843. 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. 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: 5.4 — MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
EPSS (FIRST): 0.3% probability of exploitation in the next 30 days, higher than 21.4% of all scored CVEs
CISA KEV: Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority: 3.6/10 — 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-2026-12298 being exploited?

It currently carries a trending score of 11 in the Threadlinqs vulnerability feed.

Affected products and versions

Mozilla: Firefox, Thunderbird

How to fix CVE-2026-12298

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-2026-12298

1 tracked threat in the Threadlinqs corpus references CVE-2026-12298, either in the campaign’s CVE list or as an indicator on the campaign record.

Multiple Vulnerabilities in Firefox 152 Enable Remote Code Execution and Sandbox Escape (MFSA 2026-57) — HIGH · 2026-06-18

Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on 2026-10-10. This product uses the NVD API but is not endorsed or certified by the NVD.

CVE-2026-12298 — Mozilla Firefox