CVE-2026-4701CRITICAL 9.8EPSS p36.4%

CVE-2026-4701CVE-2026-4701

Description

Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

Scoring

CVSS 3.19.8 (CRITICAL)
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS0.46% probability of exploitation · percentile 36.4% · 2026-06-19T12:03:05Z
Published2026-03-24
Last modified2026-04-13

Underlying weaknesses· 1

CWE-416

References

  1. https://bugzilla.mozilla.org/show_bug.cgi?id=2009303
  2. https://www.mozilla.org/security/advisories/mfsa2026-20/
  3. https://www.mozilla.org/security/advisories/mfsa2026-22/
  4. https://www.mozilla.org/security/advisories/mfsa2026-23/
  5. https://www.mozilla.org/security/advisories/mfsa2026-24/

1

TypeTargetConfidenceTier
WeaknessUse After Freecwe-4160%live

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Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.