by Kastro
Paper/Archive/CVE-2026-4702

CVE-2026-4702

Mozilla Firefox — JIT miscompilation in the JavaScript Engine component

EPSS 0.7%CVSS 9.8
critical.is priorityof 100
40
CVSS 9.8 (ADP, NVD agree)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 53.2.532 × 2010.6No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

JIT miscompilation in the JavaScript Engine component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

Affected

ProductAffectedFixed inSource
Firefoxsee advisory140.9CNA
Thunderbirdsee advisory140.9CNA

Scores by source

CISA ADP9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refbugzilla.mozilla.org/show_bug.cgi?id=2013560refmozilla.org/security/advisories/mfsa2026-20refmozilla.org/security/advisories/mfsa2026-22refmozilla.org/security/advisories/mfsa2026-23refmozilla.org/security/advisories/mfsa2026-24