Paper/Archive/CVE-2026-4723

CVE-2026-4723

Mozilla Firefox — Use-after-free in the JavaScript Engine component

EPSS 0.6%CVSS 9.8

critical.is priorityof 100

39

CVSS 9.8 (ADP, NVD agree)9.8 / 10 × 3029.4 Not in CISA KEV+300.0 EPSS percentile 49.6.496 × 209.9 No public exploit+100.0 SSVC exploitation: none+100.0

Description · from the CVE record

Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 149 and Thunderbird 149.

Affected

ProductAffectedFixed inSource

Firefoxsee advisory149CNA

Thunderbirdsee advisory149CNA

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=2013573 refmozilla.org/security/advisories/mfsa2026-20 refmozilla.org/security/advisories/mfsa2026-23