CVE-2026-4702 | BDVDB-2026-322199 Detail

MozillaFirefox

Description#

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

Impact#

Per CVSS v3.1: confidentiality impact high, integrity impact high, availability impact high. Attack vector: network.

Weaknesses#

CWE-843 Access of Resource Using Incompatible Type ('Type Confusion')

References#

Exploit#

No public exploit known

History#

Version 12026-03-24Record published in the CVE List.
Version 22026-04-13Most recent update recorded in the CVE List.

Published

Published: 2026-03-24
Last modified: 2026-04-13

Vendor information

Vendor: Mozilla
Product: Firefox

All Mozilla vulnerabilities

Score

9.8 Critical

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 54.1.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Type Confusion

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
Not stated
Fixed
140.9
Vulnerable
Not stated
Fixed
149

Scoring System

CVSS v4.0

Not available

CVSS v3.1

9.8 Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Privileges Required	None
User Interaction	None
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).